G M: 1. It changes the temp file handling to use the template and the current directory for windows, matching how it works on other platforms.
2. It re-enables the temp file handling for mingw that regressed.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@192073 91177308-0d34-0410-b5e6-96231b3b80d8