Implement g_content_type_is_mime_type() (clone of win32's)
Implement g_content_type_is_mime_type() (clone of win32's)

Add missing function, copying from gcontenttype-win32.c per Patrick
Griffis (Comment #55 of bug report)

https://bugzilla.gnome.org/show_bug.cgi?id=734946

johne53/MB3Glib,endlessm/glib,endlessm/glib,johne53/MB3Glib,johne53/MB3Glib,endlessm/glib,endlessm/glib,johne53/MB3Glib,johne53/MB3Glib,endlessm/glib,johne53/MB3Glib