* 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.
