Update clang to r339409.

Change-Id: I800772d2d838223be1f6b40d490c4591b937fca2
diff --git a/linux-x64/clang/include/llvm/Support/MutexGuard.h b/linux-x64/clang/include/llvm/Support/MutexGuard.h
index 07b64b6..641d64d 100644
--- a/linux-x64/clang/include/llvm/Support/MutexGuard.h
+++ b/linux-x64/clang/include/llvm/Support/MutexGuard.h
@@ -23,7 +23,7 @@
   /// these on the stack at the top of some scope to be assured that C++
   /// destruction of the object will always release the Mutex and thus avoid
   /// a host of nasty multi-threading problems in the face of exceptions, etc.
-  /// @brief Guard a section of code with a Mutex.
+  /// Guard a section of code with a Mutex.
   class MutexGuard {
     sys::Mutex &M;
     MutexGuard(const MutexGuard &) = delete;