Wayland Protocol 1.38 released - tchncs

This full packed release comes with three new staging protocols: * system bell - allowing e.g. terminal emulators to hand off system bell alerts to the compositor for among other things accessibility purposes * fifo - for implementing first in first out surface content update behavior * commit timing - for adding time constraints to surface content update Other than this, the presentation timing protocol protocol got a version minor bump describing how to deal with variable refresh rate. Other protocols saw the regular clarifications and bug fixes, and some deprecated events is now properly indicated as such in the XML. Please see individual commits for details.