lib/Basic/Targets.cpp: mingw-w64 should define __MINGW32__, too.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@127238 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Basic/Targets.cpp b/lib/Basic/Targets.cpp
index 55321f2..a9667bb 100644
--- a/lib/Basic/Targets.cpp
+++ b/lib/Basic/Targets.cpp
@@ -1629,6 +1629,7 @@
     WindowsX86_64TargetInfo::getTargetDefines(Opts, Builder);
     DefineStd(Builder, "WIN64", Opts);
     Builder.defineMacro("__MSVCRT__");
+    Builder.defineMacro("__MINGW32__");
     Builder.defineMacro("__MINGW64__");
     Builder.defineMacro("__declspec", "__declspec");
   }