re PR middle-end/56461 (GCC is leaking lots of memory)

re PR middle-end/56461 (GCC is leaking lots of memory)

	PR middle-end/56461
	* tree-flow.h (edge_var_map_vector): Change into va_heap, vl_embed
	vector.
	* tree-ssa.c (redirect_edge_var_map_add): Use vec_safe_reserve and
	vec_safe_push, always update *slot.
	(redirect_edge_var_map_clear): Use vec_free.
	(redirect_edge_var_map_dup): Use vec_safe_copy and vec_safe_reserve.
	(free_var_map_entry): Use vec_free.
	* tree-cfgcleanup.c (remove_forwarder_block_with_phi): Use
	FOR_EACH_VEC_SAFE_ELT instead of FOR_EACH_VEC_ELT.

From-SVN: r196313