libc: Fix 'index' symbol export.

The C library didn't export the 'index' symbol, but its C++ name-mangling
instead, which broke the ABI and prevented some applications from loading
properly.

The main reason was that the implementation under bionic/index.cpp relied
on the declaration to specify that the function has C linkage.

However, the declaration for index() was removed from both <string.h>
and <strings.h> in a recent patch, which made the compiler think it was
ok to compile the function with C++ linkage instead!

This patch does the following:

- Move index() definition to bionic/ndk_cruft.cpp and ensure it uses
  C linkage.

  Note that this removes index() from the 64-bit library entirely, this
  is intentional and will break source compatibility. Simply replacing
  an index() call with the equivalent strchr() should be enough to fix
  this in third-party code.

- Remove bionic/index.cpp from the tree and build files.

- Remove x86 assembly implementation from arch-x86/ to avoid conflict
  with the one in ndk_cruft.cpp

BUG=15606653

Change-Id: I816b589f69c8f8a6511f6be6195d20cf1c4e8123
diff --git a/libc/arch-arm/arm.mk b/libc/arch-arm/arm.mk
index 26690ce..38301bc 100644
--- a/libc/arch-arm/arm.mk
+++ b/libc/arch-arm/arm.mk
@@ -12,7 +12,6 @@
     bionic/mmap.cpp
 
 libc_common_src_files_arm += \
-    bionic/index.cpp \
     bionic/memchr.c \
     bionic/memrchr.c \
     bionic/strchr.cpp \
diff --git a/libc/arch-mips/mips.mk b/libc/arch-mips/mips.mk
index 529e284..fe5e24d 100644
--- a/libc/arch-mips/mips.mk
+++ b/libc/arch-mips/mips.mk
@@ -12,7 +12,6 @@
      bionic/mmap.cpp
 
 libc_common_src_files_mips += \
-    bionic/index.cpp \
     bionic/memchr.c \
     bionic/memcmp.c \
     bionic/memmove.c \
diff --git a/libc/arch-x86/atom/atom.mk b/libc/arch-x86/atom/atom.mk
index abe940d..3f28fb2 100644
--- a/libc/arch-x86/atom/atom.mk
+++ b/libc/arch-x86/atom/atom.mk
@@ -1,6 +1,5 @@
 libc_bionic_src_files_x86 += \
     arch-x86/atom/string/sse2-bzero-atom.S \
-    arch-x86/atom/string/sse2-index-atom.S \
     arch-x86/atom/string/sse2-memchr-atom.S \
     arch-x86/atom/string/sse2-memrchr-atom.S \
     arch-x86/atom/string/sse2-memset-atom.S \
diff --git a/libc/arch-x86/atom/string/sse2-index-atom.S b/libc/arch-x86/atom/string/sse2-index-atom.S
deleted file mode 100644
index d51e1d4..0000000
--- a/libc/arch-x86/atom/string/sse2-index-atom.S
+++ /dev/null
@@ -1,32 +0,0 @@
-/*
-Copyright (c) 2011, Intel Corporation
-All rights reserved.
-
-Redistribution and use in source and binary forms, with or without
-modification, are permitted provided that the following conditions are met:
-
-    * Redistributions of source code must retain the above copyright notice,
-    * this list of conditions and the following disclaimer.
-
-    * Redistributions in binary form must reproduce the above copyright notice,
-    * this list of conditions and the following disclaimer in the documentation
-    * and/or other materials provided with the distribution.
-
-    * Neither the name of Intel Corporation nor the names of its contributors
-    * may be used to endorse or promote products derived from this software
-    * without specific prior written permission.
-
-THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
-ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
-WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
-DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
-ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
-(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
-LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
-ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
-(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
-SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
-*/
-
-#define strchr  index
-#include "sse2-strchr-atom.S"
diff --git a/libc/arch-x86/generic/generic.mk b/libc/arch-x86/generic/generic.mk
index 62e81b7..4aee5dc 100644
--- a/libc/arch-x86/generic/generic.mk
+++ b/libc/arch-x86/generic/generic.mk
@@ -1,5 +1,4 @@
 libc_bionic_src_files_x86 += \
-    arch-x86/atom/string/sse2-index-atom.S \
     arch-x86/atom/string/sse2-memchr-atom.S \
     arch-x86/atom/string/sse2-memrchr-atom.S \
     arch-x86/atom/string/sse2-strchr-atom.S \
diff --git a/libc/arch-x86/silvermont/silvermont.mk b/libc/arch-x86/silvermont/silvermont.mk
index 9640a24..176bee3 100644
--- a/libc/arch-x86/silvermont/silvermont.mk
+++ b/libc/arch-x86/silvermont/silvermont.mk
@@ -17,7 +17,6 @@
     arch-x86/atom/string/sse2-memrchr-atom.S \
     arch-x86/atom/string/sse2-strchr-atom.S \
     arch-x86/atom/string/sse2-strrchr-atom.S \
-    arch-x86/atom/string/sse2-index-atom.S \
     arch-x86/atom/string/sse2-strnlen-atom.S \
     arch-x86/atom/string/sse2-wcschr-atom.S \
     arch-x86/atom/string/sse2-wcsrchr-atom.S \
diff --git a/libc/bionic/index.cpp b/libc/bionic/index.cpp
deleted file mode 100644
index cc22d81..0000000
--- a/libc/bionic/index.cpp
+++ /dev/null
@@ -1,35 +0,0 @@
-/*-
- * Copyright (c) 1990 The Regents of the University of California.
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- * 1. Redistributions of source code must retain the above copyright
- *    notice, this list of conditions and the following disclaimer.
- * 2. Redistributions in binary form must reproduce the above copyright
- *    notice, this list of conditions and the following disclaimer in the
- *    documentation and/or other materials provided with the distribution.
- * 3. Neither the name of the University nor the names of its contributors
- *    may be used to endorse or promote products derived from this software
- *    without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
- * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
- * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
- * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
- * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
- * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
- * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
- * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
- * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
- * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
- * SUCH DAMAGE.
- */
-
-#undef _FORTIFY_SOURCE
-#include <string.h>
-
-char* index(const char* p, int ch) {
-  return __strchr_chk(p, ch, __BIONIC_FORTIFY_UNKNOWN_SIZE);
-}
diff --git a/libc/bionic/ndk_cruft.cpp b/libc/bionic/ndk_cruft.cpp
index 1ae388b..e3e640a 100644
--- a/libc/bionic/ndk_cruft.cpp
+++ b/libc/bionic/ndk_cruft.cpp
@@ -36,6 +36,7 @@
 #include <signal.h>
 #include <stdio.h>
 #include <stdlib.h>
+#include <string.h>
 #include <sys/resource.h>
 #include <sys/syscall.h>
 #include <sys/time.h>
@@ -296,4 +297,9 @@
   return 0;
 }
 
+// This was removed from POSIX 2008.
+extern "C" char* index(const char* str, int ch) {
+  return strchr(str, ch);
+}
+
 #endif