tree-flow.h (ssa_names): Change the type to VEC(tree,gc).

tree-flow.h (ssa_names): Change the type to VEC(tree,gc).

	* tree-flow.h (ssa_names): Change the type to VEC(tree,gc).
	(num_ssa_names): Use VEC_length.
	(ssa_names): Use VEC_index.
	* tree-ssanames.c (ssa_names): Change the type to
	VEC(tree,gc).
	(init_ssanames, fini_ssa_names, make_ssanames,
	release_ssa_name): Update uses of ssa_names.

From-SVN: r98843