Revert "tls: Set umask before creating temporary file"

This reverts commit 1fc1558e7ac11102a4bc479a57de76c4f4f42c46.

There are a few issues with this change.

1) verify_tmp_dir is created 0700 *before* mkstemp() is called
   So the umask for the temporary file doesn't matter

2) the server is threaded, and umask() is *global* to the process
   So there is no "before" mkstemp() and "after" mkstemp().

The Coverity warning is (in this case) a false positive.