[Bug sanitizer/95137] Sanitizers seem to be missing support for coroutines

[iains at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95137

--- Comment #13 from Iain Sandoe <iains at gcc dot gnu.org> ---
Created attachment 48572
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=48572&action=edit
fix for most of the UBSAN fails

Most of the UBSAN fails are from a single cause; I reused the built DTOR tree
on both resume and destroy edges from the await.

There is a single remaining UBSAN fail (which is unrelated).

I don't expect this to make any difference to the initial reported fail.