Update aosp/master clang for rebase to r230699.

Change-Id: I6a546ab3d4ae37119eebb735e102cca4f80ab520
diff --git a/lib/Headers/module.modulemap b/lib/Headers/module.modulemap
index 3c42477..062464e 100644
--- a/lib/Headers/module.modulemap
+++ b/lib/Headers/module.modulemap
@@ -1,4 +1,4 @@
-module _Builtin_intrinsics [system] {
+module _Builtin_intrinsics [system] [extern_c] {
   explicit module altivec {
     requires altivec
     header "altivec.h"