gtkmm3: Allow wayland or x11 in distro features
gtkmm3: Allow wayland or x11 in distro features

Fixes build with no-x11 distros

Signed-off-by: Khem Raj <729d64b6f67515e258459a5f6d20ec88b2caf8df@gmail.com>
Cc: Andreas Müller <d72a15aaaca3a7afa855175c72dc8d2e05931e32@gmail.com>

openembedded/meta-openembedded,openembedded/meta-openembedded,openembedded/meta-openembedded,openembedded/meta-openembedded,openembedded/meta-openembedded,openembedded/meta-openembedded,openembedded/meta-openembedded,openembedded/meta-openembedded