add support for mingw64 target triples.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@78797 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Support/Triple.cpp b/lib/Support/Triple.cpp
index 7c028f4..a81fb5b 100644
--- a/lib/Support/Triple.cpp
+++ b/lib/Support/Triple.cpp
@@ -63,6 +63,7 @@
   case FreeBSD: return "freebsd";
   case Linux: return "linux";
   case MinGW32: return "mingw32";
+  case MinGW64: return "mingw64";
   case NetBSD: return "netbsd";
   case OpenBSD: return "openbsd";
   case Win32: return "win32";
@@ -171,6 +172,8 @@
     OS = Linux;
   else if (OSName.startswith("mingw32"))
     OS = MinGW32;
+  else if (OSName.startswith("mingw64"))
+    OS = MinGW64;
   else if (OSName.startswith("netbsd"))
     OS = NetBSD;
   else if (OSName.startswith("openbsd"))