* core: handle rerendering when frameCallback is pending
* core: log when skipping label updates
* asyncResourceGatherer: remove busy and use loopMutex
Makes getAssetById fail less often and thus labels get more stable
updates
* asyncResourceGatherer: revision locking
`assetsMutex` was not needed, since `apply` only gets called from the
main thread and resources are also only aquired via the main thread.
`preloadTargets`, previously kinda guarded by the `busy` flag are now
locked as suggested in #367 (but via a copy of `peloadTargets`).
`apply` now returns a boolean so that the locking of preloadTargets in
combination with checking `preloadTargets.empty()` is a bit nicer.
* asyncResourceGatherer: remove explicit template arg for unique lock
* widgets: add missing virtual destructor
destructor is missing and as a consequence all sub classes gets wrongly
destructed reported as "new-delete-type-mismatch" by asan.
* gatherer: free memory allocated by pango
with pango_parse_markup its up to the caller of the function to free the
pointer to the text returned stored in this buf.
* core: add destructor and free devices
add a destructor and free both drmDevice and gbmDevice, leaks reported
by asan.
* core: free xkb allocated state and keymap
free xkb state and keymap on destruction to prevent leak on exit and
less asan spam.
* locksurface: destroy the surface frame on done
the callback was never being destroyed and is leaking on each
frameCallback creation, call wl_callback_destroy in onCallback() and
free the memory. reported with asan.
