Start making use of "pretty stack dumps" to get 
better crash info when clang crashes.  Step #2 of many.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@66078 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/Driver/clang.cpp b/Driver/clang.cpp
index 87447c4..5f8bb36 100644
--- a/Driver/clang.cpp
+++ b/Driver/clang.cpp
@@ -50,6 +50,7 @@
 #include "llvm/Support/ManagedStatic.h"
 #include "llvm/Support/MemoryBuffer.h"
 #include "llvm/Support/PluginLoader.h"
+#include "llvm/Support/PrettyStackTrace.h"
 #include "llvm/Support/Timer.h"
 #include "llvm/System/Host.h"
 #include "llvm/System/Path.h"
@@ -1561,6 +1562,7 @@
 int main(int argc, char **argv) {
   llvm::cl::ParseCommandLineOptions(argc, argv, " llvm clang cfe\n");
   llvm::sys::PrintStackTraceOnErrorSignal();
+  llvm::PrettyStackTraceProgram X(argc, argv);
   
   if (TimeReport)
     ClangFrontendTimer = new llvm::Timer("Clang front-end time");