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/lib/Frontend/InitHeaderSearch.cpp b/lib/Frontend/InitHeaderSearch.cpp
index d2890f0..d2edc94 100644
--- a/lib/Frontend/InitHeaderSearch.cpp
+++ b/lib/Frontend/InitHeaderSearch.cpp
@@ -472,7 +472,8 @@
 
   case llvm::Triple::Win32:
     if (triple.getEnvironment() == llvm::Triple::MSVC ||
-        triple.getEnvironment() == llvm::Triple::Itanium)
+        triple.getEnvironment() == llvm::Triple::Itanium ||
+        triple.getObjectFormat() == llvm::Triple::MachO)
       return;
     break;
   }