swtpm: Replace mkstemp with g_mkstemp_full (Coverity)

Replace mkstemp with g_mkstemp_full and pass parameters that lead to
the same mode bits and file opening flags and mkstemp had. This addresses
a Coverity complaint regarding missing application of umask before
mkstemp.

Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>
1 file changed