fix #648:

fix #648:

Win32 only: reading a pathname from an environment var requires us to read it in as unicode somehow and convert it to utf8. Using _wgetenv should work under all circumstances on NT, using getenv and g_locale_to_utf8 on Windows OT is the best we can do in this case.

git-svn-id: http://anonsvn.wireshark.org/wireshark/trunk@17024 f5534014-38df-0310-8fa8-9805f1628bb7