re PR middle-end/51761 (ICE in verify_gimple_stmt, at tree-cfg.c:4241)

	PR middle-end/51761
	* gimple.h (struct gimplify_ctx): Add in_cleanup_point_expr
	field.
	* gimplify.c (gimplify_cleanup_point_expr): Save and set
	in_cleanup_point_expr before gimplify_stmt call and restore it
	afterwards.
	(gimplify_target_expr): Don't add {CLOBBER} cleanup if
	in_cleanup_point_expr is false.

	* gcc.c-torture/compile/pr51761.c: New test.

From-SVN: r182914