xfixes: Allow the client to upgrade the fixes protocol version

If you say FixesQueryVersion twice we remember whatever the second
version number was. With just libXfixes this isn't an issue because the
request is hidden in extension setup, but libxcb-xfixes doesn't do that
for you, which means the second one can _lower_ the requested fixes
version, disabling requests that the client thought it had enabled.

Paper over this by allowing the version number to be raised but not
lowered. Also go ahead and delete the minor version number from the
client state since xfixes doesn't have minor versions (yet, anyway).
5 jobs for xfixes-version-slack in 6 minutes and 1 second (queued for 8 seconds)
Status Job ID Name Coverage
  Docker Image
passed debian-buster #11452175

00:00:21

 
  Build And Test
passed autotools #11452176

00:05:39

passed meson #11452177

00:02:12

passed meson-noglamor #11452178

00:01:29

passed mingw-cross-build #11452179

00:00:42