[Bug libstdc++/83395] [7/8 Regression] is_invocable_r fails for cv-qualified void return type

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83395

Jonathan Wakely <redi at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
      Known to work|                            |7.2.0
   Target Milestone|---                         |7.3
            Summary|is_invocable_r fails for    |[7/8 Regression]
                   |cv-qualified void return    |is_invocable_r fails for
                   |type                        |cv-qualified void return
                   |                            |type
      Known to fail|                            |7.2.1, 8.0

--- Comment #1 from Jonathan Wakely <redi at gcc dot gnu.org> ---
And similarly for is_nothrow_invocable_r.

I broke this with the fix for Bug 82254