coroutines: Copy attributes to the outlined functions [PR95518,PR95813]

coroutines: Copy attributes to the outlined functions [PR95518,PR95813]

We had omitted the copying of function attributes, we now copy
the used, alignment, section values from the original decal and
the complete set of function attributes.  It is likely that
some function attributes don't really make sense for coroutines,
but that can be disgnosed separately. Also mark the outlined
functions as artificial, since they are; some diagnostic
processing tests this.

gcc/cp/ChangeLog:

	PR c++/95518
	PR c++/95813
	* coroutines.cc (act_des_fn): Copy function
	attributes onto the outlined coroutine helpers.

gcc/testsuite/ChangeLog:

	PR c++/95518
	PR c++/95813
	* g++.dg/coroutines/pr95518.C: New test.
	* g++.dg/coroutines/pr95813.C: New test.