[!TARGET_API_MAC_CARBON] Include Scrap.h.

[!TARGET_API_MAC_CARBON] Include Scrap.h.
[MAC_OSX] (install_service_handler): Rename from init_service_handler.
All callers changed.  Return OSStatus value.
(Selection): New typedef.  Use instead of ScrapRef.
(mac_get_selection_from_symbol): Rename from get_scrap_from_symbol.
(mac_valid_selection_target_p): Rename from valid_scrap_target_type_p.
(mac_clear_selection): Rename from clear_scrap.
(get_flavor_type_from_symbol): New argument SEL and subsume function of
scrap_has_target_type.  All uses changed.
(mac_get_selection_ownership_info, mac_valid_selection_value_p)
(mac_selection_has_target_p): New functions.
(mac_put_selection_value): Rename from put_scrap_string.
(mac_get_selection_value): Rename from get_scrap_string.
(mac_get_selection_target_list): Rename from get_scrap_target_type_list.
(put_scrap_private_timestamp, scrap_has_target_type)
(get_scrap_private_timestamp): Remove functions.
(SCRAP_FLAVOR_TYPE_EMACS_TIMESTAMP): Remove define.
(x_own_selection, x_get_local_selection):
Use mac_valid_selection_value_p.
(x_own_selection): Don't use put_scrap_private_timestamp.
Record OWNERSHIP-INFO into Vselection_alist instead.
(x_get_local_selection): Don't check type if request is local.
(Fx_selection_owner_p): Don't use get_scrap_private_timestamp.
Detect ownership change with OWNERSHIP-INFO in Vselection_alist instead.