Look at the TMP environment variable as well.

llvm-svn: 69638
diff --git a/clang/lib/Driver/Driver.cpp b/clang/lib/Driver/Driver.cpp
index f0eadf7..d88f1b3 100644
--- a/clang/lib/Driver/Driver.cpp
+++ b/clang/lib/Driver/Driver.cpp
@@ -1114,6 +1114,8 @@
   if (!TmpDir)
     TmpDir = ::getenv("TEMP");
   if (!TmpDir)
+    TmpDir = ::getenv("TMP");
+  if (!TmpDir)
     TmpDir = "/tmp";
   llvm::sys::Path P(TmpDir);
   P.appendComponent("cc");