Add patches to fix startup with no input devices attached
The DRM backend overwrites the require-input
config option, causing
the compositor to fail starting (and crash) if no input device is
attached.
This commit imports an upstream patch for honoring this config option, as well as a second one for cleanly exiting in case of a failure instead of crashing as was previously the case (the latter isn't strictly required, but it is small enough to be worth it).