This patch fixes test failures that occur on Windows because
the tests attempt to generate two distinct temp file names but
get the same name both time.
The fix for this is to create the first temp file before requesting
a second temporary file name. This ensures that the second name
will be unique.
git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@302382 91177308-0d34-0410-b5e6-96231b3b80d8
