middle-end/99281 - avoid bitfield stores into addressable types

middle-end/99281 - avoid bitfield stores into addressable types

This avoids doing bitfield stores into the return object of calls
when using return-slot optimization and the type is addressable.
Instead we have to pass down the original target RTX to the call
expansion which otherwise tries to create a new temporary.

2021-02-26  Richard Biener  <rguenther@suse.de>

	PR middle-end/99281
	* expr.c (store_field): For calls with return-slot optimization
	and addressable return type expand the store directly.

	* g++.dg/pr99218.C: New testcase.