c++, coroutines: Partial reversion of r12-8308-g15a176a833f23e [PR105426].

c++, coroutines: Partial reversion of r12-8308-g15a176a833f23e [PR105426].

The changes to fix PR 105287 included a tightening of the constraints on which
variables are promoted to frame copies.  This has exposed that we are failing
to name some variables that should be promoted.

We avoid the use of DECL_UID to build anonymous symbols since that might not
be stable for -fcompare-debug.

The long-term fix is to address the cases where the naming has been missed,
but for the short-term (and for the GCC-12 branch) backing out the additional
constraint is proposed.

Signed-off-by: Iain Sandoe <iain@sandoe.co.uk>
	PR c++/105426

gcc/cp/ChangeLog:

	* coroutines.cc (register_local_var_uses): Allow promotion of unnamed
	temporaries to coroutine frame copies.

(cherry picked from commit 3d8d093e820b10a4b4b2af8949a368377c0888cb)