Update aosp/master Clang for rebase to r275480

Bug: http://b/31320715

This merges commit ac9cc4764cf47a6c3f031687d8592e080c9f5001 from
aosp/dev.

Test: Build AOSP and run RenderScript tests (host tests for slang and
libbcc, RsTest, CTS)

Change-Id: Ic2875e5c3673c83448cd7d1013861e42947b1b55
diff --git a/lib/Edit/RewriteObjCFoundationAPI.cpp b/lib/Edit/RewriteObjCFoundationAPI.cpp
index 9f71168..482c0f6 100644
--- a/lib/Edit/RewriteObjCFoundationAPI.cpp
+++ b/lib/Edit/RewriteObjCFoundationAPI.cpp
@@ -1077,6 +1077,9 @@
     case CK_BuiltinFnToFnPtr:
     case CK_ZeroToOCLEvent:
       return false;
+
+    case CK_BooleanToSignedIntegral:
+      llvm_unreachable("OpenCL-specific cast in Objective-C?");
     }
   }