weston: release keyboard/touch/pointer objects
weston: release keyboard/touch/pointer objects

This patch adds the missing calls to release when the seat has capabilities
changes. It also fixes a missing release of the touch object and a leak with
old clients.

Signed-off-by: David FORT <1a73af9e7ae00182733b2292511b814be66f065f@hardening-consulting.com>
Reviewed-by: Derek Foreman <2f97e0f0bc172406aab8ccd42dab54c95bab8759@osg.samsung.com>
Reviewed-by: Daniel Stone <62e7e355d5d8400fa8384448796af0bf6be4ffae@collabora.com>

Gnurou/weston,krezovic/weston,sir-murray/weston,giucam/weston,Fantu/compositor-spice,kwm81/weston,Fantu/compositor-spice,giucam/weston,krezovic/weston,sir-murray/weston,Fantu/compositor-spice,kwm81/weston,Gnurou/weston