MC: don't create a backtrace for diagnostics.

For better or worse, this is currently the normal error reporting path
when dealing with backend errors from inline assembly. It's not just
internal compiler issues that come through here, so we shouldn't be
creating a backtrace on this path.

rdar://16329947

llvm-svn: 203979

llvm/lib/MC/MCContext.cpp

@@ -353,7 +353,7 @@ void MCContext::FatalError(SMLoc Loc, const Twine &Msg) {
   // If we have a source manager and a location, use it. Otherwise just
   // use the generic report_fatal_error().
   if (!SrcMgr || Loc == SMLoc())
-    report_fatal_error(Msg);
+    report_fatal_error(Msg, false);
 
   // Use the source manager to print the message.
   SrcMgr->PrintMessage(Loc, SourceMgr::DK_Error, Msg);