return auto_vec from more dominance functions

return auto_vec from more dominance functions

This ensures the vector gets cleaned up by the caller when appropriate.

Signed-off-by: Trevor Saunders <tbsaunde@tbsaunde.org>
gcc/ChangeLog:

	* dominance.c (get_dominated_to_depth): Return auto_vec<basic_block>.
	* dominance.h (get_dominated_to_depth): Likewise.
	(get_all_dominated_blocks): Likewise.
	* cfgcleanup.c (delete_unreachable_blocks): Adjust.
	* gcse.c (hoist_code): Likewise.
	* tree-cfg.c (remove_edge_and_dominated_blocks): Likewise.
	* tree-parloops.c (oacc_entry_exit_ok): Likewise.
	* tree-ssa-dce.c (eliminate_unnecessary_stmts): Likewise.
	* tree-ssa-phiprop.c (pass_phiprop::execute): Likewise.