Remove dependency on arm_neon.h

Remove the global clang dependency on arm_neon.h and the rules to
generate arm_neon.h, they are left over from when $(CLANG) might point
to a locally built copy of clang and are superseded by
clang-tblgen-rules.mk.  Fixes a circular dependency between clang,
clang-tblgen, and arm_neon.h.

Bug: 25874490
Change-Id: I0e6b5e04c4a72d2aaaf4ce63b62a09caf5a40fc9
diff --git a/Android.mk b/Android.mk
index 4faf6c5..f85cbee 100644
--- a/Android.mk
+++ b/Android.mk
@@ -28,7 +28,6 @@
   lib/Frontend \
   lib/Frontend/Rewrite \
   lib/FrontendTool \
-  lib/Headers \
   lib/Index \
   lib/Lex \
   lib/Parse \
diff --git a/lib/Headers/Android.mk b/lib/Headers/Android.mk
deleted file mode 100644
index c1df621..0000000
--- a/lib/Headers/Android.mk
+++ /dev/null
@@ -1,11 +0,0 @@
-LOCAL_PATH:= $(call my-dir)
-
-include $(CLEAR_VARS)
-
-$(TARGET_OUT_HEADERS)/clang/arm_neon.h: TBLGEN_LOCAL_MODULE := arm_neon.h
-$(TARGET_OUT_HEADERS)/clang/arm_neon.h: $(CLANG_ROOT_PATH)/include/clang/Basic/arm_neon.td \
-    $(CLANG_TBLGEN)
-	$(call transform-host-clang-td-to-out,arm-neon)
-
-# Make sure when clang is used, arm_neon.h does exist.
-$(CLANG): | $(TARGET_OUT_HEADERS)/clang/arm_neon.h