Update Clang for rebase to r212749.

This also fixes a small issue with arm_neon.h not being generated always.

Includes a cherry-pick of:
r213450 - fixes mac-specific header issue
r213126 - removes a default -Bsymbolic on Android

Change-Id: I2a790a0f5d3b2aab11de596fc3a74e7cbc99081d
diff --git a/test/SemaCXX/undefined-internal.cpp b/test/SemaCXX/undefined-internal.cpp
index 1cb0708..f32036a 100644
--- a/test/SemaCXX/undefined-internal.cpp
+++ b/test/SemaCXX/undefined-internal.cpp
@@ -1,10 +1,7 @@
 // RUN: %clang_cc1 -fsyntax-only -verify %s
 
 // Make sure we don't produce invalid IR.
-// RUN: %clang_cc1 -triple %itanium_abi_triple -emit-llvm-only %s
-
-// FIXME: Itanium shouldn't be necessary; the test should pass
-// in MS mode too.
+// RUN: %clang_cc1 -emit-llvm-only %s
 
 namespace test1 {
   static void foo(); // expected-warning {{function 'test1::foo' has internal linkage but is not defined}}