x11: Fix bad logic in axis check

https://bugzilla.gnome.org/show_bug.cgi?id=711540
timeline: Fix bad logic in check

https://bugzilla.gnome.org/show_bug.cgi?id=711540
build: Add -Werror=logical-op

Caught a couple of checks that evaluated to always true.

https://bugzilla.gnome.org/show_bug.cgi?id=711540