* tree-ssa-dse.c (initialize_ao_ref_for_dse): Handle
	strncpy.  Drop some trivial dead code.
	(maybe_trim_memstar_call): Handle strncpy.

	* gcc.dg/tree-ssa/ssa-dse-37.c: New test.
	* gcc.dg/tree-ssa/ssa-dse-38.c: New test.

From-SVN: r273606