* calls.c (emit_call_1): Set MEM_EXPR on call's MEM.
	* var-tracking.c (prepare_call_arguments): Use MEM_EXPR on
	call's MEM.  Handle functions returning aggregate through a hidden
	first pointer.  For virtual calls add clobbered pc to call arguments
	chain.
	* dwarf2out.c (gen_subprogram_die): Emit
	DW_AT_GNU_call_site_target_clobbered if DW_AT_GNU_call_site_target
	can't be emitted.

From-SVN: r171036