Pull mkstemp() into tempfile.c. That's the only place we use it now, and

Pull mkstemp() into tempfile.c. That's the only place we use it now, and
it's arguably the only place we _should_ use it. Add create_tempdir() to
tempfile.c and use it to create a temp directory for IP maps. This
should fix bug 3530.

(This still doesn't work on IE 8 / Vista here. IE gives an access denied
error in OpenLayers.js, but this is a separate issue).

git-svn-id: http://anonsvn.wireshark.org/wireshark/trunk@28920 f5534014-38df-0310-8fa8-9805f1628bb7