configure: require glib 2.22

This provides g_ptr_array_new_with_free_func, as well as a few
other functions that we've been hacking around in glib-compat.h.
Cleaning up the compatibility headers will come later.
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: NJohn Snow <jsnow@redhat.com>
Reviewed-by: NMarkus Armbruster <armbru@redhat.com>
Reviewed-by: NAlex Bennée <alex.bennee@linaro.org>
Message-id: 1431469140-22208-2-git-send-email-jsnow@redhat.com

configure

@@ -2779,12 +2779,7 @@ fi
 ##########################################
 # glib support probe
 
-if test "$mingw32" = yes; then
-    # g_poll is required in order to integrate with the glib main loop.
-    glib_req_ver=2.20
-else
-    glib_req_ver=2.12
-fi
+glib_req_ver=2.22
 glib_modules=gthread-2.0
 if test "$modules" = yes; then
     glib_modules="$glib_modules gmodule-2.0"