Fix `gui-backend-selection-owner-p' on Haiku

Fix `gui-backend-selection-owner-p' on Haiku

* src/haiku_select.cc (be_update_clipboard_count): New function.
(be_set_clipboard_data): Update clipboard counts.
(BClipboard_owns_clipboard, clipboard_owner_p)
(BClipboard_owns_primary, primary_owner_p)
(BClipboard_owns_secondary, secondary_owner_p): Rename functions
somewhat.
(be_clipboard_owner_p): New function.
* src/haikuselect.c (Fhaiku_selection_put)
(Fhaiku_selection_owner_p): Update selection counts as well.
* src/haikuselect.h: Update prototypes.