re PR c/33238 (ICE on statement expression using variable-sized structure in tree_low_cst, at tree.c:4502)

	PR c/33238
	PR c/27301
	* gimplify.c (gimplify_vla_decl): New function.
	(gimplify_decl_expr): Move VLA decl handling to gimplify_vla_decl.
	Call it.
	(gimplify_target_expr): Handle variable length TARGET_EXPRs.

	* gcc.c-torture/execute/20070919-1.c: New test.
	* gcc.dg/pr33238.c: New test.
	* gcc.dg/pr27301.c: New test.

From-SVN: r128629