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/Index/SimpleFormatContext.h b/lib/Index/SimpleFormatContext.h
index 147323a..a460863 100644
--- a/lib/Index/SimpleFormatContext.h
+++ b/lib/Index/SimpleFormatContext.h
@@ -37,7 +37,7 @@
   SimpleFormatContext(LangOptions Options)
       : DiagOpts(new DiagnosticOptions()),
         Diagnostics(new DiagnosticsEngine(new DiagnosticIDs,
-                                          DiagOpts.getPtr())),
+                                          DiagOpts.get())),
         Files((FileSystemOptions())),
         Sources(*Diagnostics, Files),
         Rewrite(Sources, Options) {
@@ -47,8 +47,7 @@
   ~SimpleFormatContext() { }
 
   FileID createInMemoryFile(StringRef Name, StringRef Content) {
-    const llvm::MemoryBuffer *Source =
-        llvm::MemoryBuffer::getMemBuffer(Content);
+    llvm::MemoryBuffer *Source = llvm::MemoryBuffer::getMemBuffer(Content);
     const FileEntry *Entry =
         Files.getVirtualFile(Name, Source->getBufferSize(), 0);
     Sources.overrideFileContents(Entry, Source);