use G_OS_WIN32 instead of _WINDOWS
use G_OS_WIN32 instead of _WINDOWS

svn path=/trunk/; revision=1552

jstedfast/gmime,zsx/gmime,jstedfast/gmime,GNOME/gmime,zsx/gmime,zsx/gmime,GNOME/gmime,zsx/gmime,jstedfast/gmime,GNOME/gmime