lib/Support/raw_ostream.cpp: On mingw, report_fatal_error() should not be called at dtor context.

report_fatal_error() invokes exit(). We know report_fatal_error() might not write messages to stderr when any errors were detected on FD == 2.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@127726 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Support/raw_ostream.cpp b/lib/Support/raw_ostream.cpp
index b175d20..a2ca101 100644
--- a/lib/Support/raw_ostream.cpp
+++ b/lib/Support/raw_ostream.cpp
@@ -466,6 +466,14 @@
         }
   }
 
+#ifdef __MINGW32__
+  // On mingw, global dtors should not call exit().
+  // report_fatal_error() invokes exit(). We know report_fatal_error()
+  // might not write messages to stderr when any errors were detected
+  // on FD == 2.
+  if (FD == 2) return;
+#endif
+
   // If there are any pending errors, report them now. Clients wishing
   // to avoid report_fatal_error calls should check for errors with
   // has_error() and clear the error flag with clear_error() before