re PR c/21536 (C99 array of variable length use causes segmentation fault)

	PR c/21536
	PR c/20760
	* gimplify.c (gimplify_decl_expr): Call gimplify_type_sizes
	on variable sizes types if a decl is a pointer to a VLA.
	(gimplify_type_sizes): Handle POINTER_TYPE and REFERENCE_TYPE.
	Call gimplify_type_sizes on aggregate fields.  Prevent infinite
	recursion.

	* gcc.dg/20050527-1.c: New test.

From-SVN: r100443