Removes index() from bionic.

This function has been removed from POSIX.

Unfortunately, we can't leave #define index(a, b) strchr((a), (b)) in its place
because defining a preprocessor macro for index() breaks a whole lot of code.

Bug: 13935372
Change-Id: Ifda348acde06da61c12e7ee2f8fe6950a3174dd1
diff --git a/libc/arch-arm64/arm64.mk b/libc/arch-arm64/arm64.mk
index 62974b6..223bc74 100644
--- a/libc/arch-arm64/arm64.mk
+++ b/libc/arch-arm64/arm64.mk
@@ -1,7 +1,6 @@
 # arm64 specific configs
 
 libc_common_src_files_arm64 := \
-    bionic/index.cpp \
     bionic/memchr.c \
     bionic/__memcmp16.cpp \
     bionic/memrchr.c \
diff --git a/libc/arch-mips64/mips64.mk b/libc/arch-mips64/mips64.mk
index 9a24c61..2b18042 100644
--- a/libc/arch-mips64/mips64.mk
+++ b/libc/arch-mips64/mips64.mk
@@ -1,7 +1,6 @@
 # mips64 specific configs
 
 libc_common_src_files_mips64 := \
-    bionic/index.cpp \
     bionic/memchr.c \
     bionic/memcmp.c \
     bionic/memmove.c \
diff --git a/libc/arch-x86_64/x86_64.mk b/libc/arch-x86_64/x86_64.mk
index 2f0cf2d..bd5e9c1 100644
--- a/libc/arch-x86_64/x86_64.mk
+++ b/libc/arch-x86_64/x86_64.mk
@@ -1,7 +1,6 @@
 # x86_64 specific configs
 
 libc_common_src_files_x86_64 := \
-    bionic/index.cpp \
     bionic/memchr.c \
     bionic/memrchr.c \
     bionic/strchr.cpp \
diff --git a/libc/include/string.h b/libc/include/string.h
index c9ae03b..7727c0e 100644
--- a/libc/include/string.h
+++ b/libc/include/string.h
@@ -43,7 +43,6 @@
 extern void*  memset(void *, int, size_t);
 extern void*  memmem(const void *, size_t, const void *, size_t) __purefunc;
 
-extern char*  index(const char *, int) __purefunc;
 extern char*  strchr(const char *, int) __purefunc;
 extern char* __strchr_chk(const char *, int, size_t);
 
diff --git a/libc/include/strings.h b/libc/include/strings.h
index 8f5fec5..c4d5f6c 100644
--- a/libc/include/strings.h
+++ b/libc/include/strings.h
@@ -47,7 +47,6 @@
 #define bzero(b, len) (void)(memset((b), '\0', (len)))
 
 int	 ffs(int);
-char	*index(const char *, int);
 int	 strcasecmp(const char *, const char *);
 int	 strncasecmp(const char *, const char *, size_t);