Resolving C23 issues in testglue.c

There was a very unusual logjam that delayed resolving the problems 
encountered when compiling testglue.c with a C23 compiler.  That logjam 
has now been cleared and a proposed solution is posted at Savannah on 
the PR76816 branch, since this issue has been tracked on that bug.

If you had problems building testglue.c with a C23 compiler, please test 
with the PR76816 branch and report success or failure either here on 
this list and/or at <[email protected]>.

Thank you for your patience as we addressed this matter.


-- Jacob