Remove problematic PrettyStackTrace entry added in r328276

I'm not sure /why/ this is causing issues for libclang, but it is.
Unbreak the buildbots since it's already consumed an hour of my time.

llvm-svn: 328286

clang/lib/Frontend/CompilerInstance.cpp

@@ -1170,11 +1170,6 @@ compileModuleImpl(CompilerInstance &ImportingInstance, SourceLocation ImportLoc,
   llvm::CrashRecoveryContext CRC;
   CRC.RunSafelyOnThread(
       [&]() {
-        SmallString<64> CrashInfoMessage("While building module for '");
-        CrashInfoMessage += ModuleName;
-        CrashInfoMessage += "'";
-        llvm::PrettyStackTraceString CrashInfo(CrashInfoMessage.c_str());
-
         GenerateModuleFromModuleMapAction Action;
         Instance.ExecuteAction(Action);
       },