CC Mode: Fontify a certain foo * bar class by the asymmetric space heuristic

CC Mode: Fontify a certain foo * bar class by the asymmetric space heuristic

This fixes bug #61144.  If the space around the * is "symmetric" we leave foo
* bar unfontified, a multiplication operation.  If it is "asymmetric" we
fontify it as a pointer declaration.

* lisp/progmodes/cc-engine.el (c-fdoc-assymetric-space-about-asterisk): New
macro, extracted from c-forward-decl-or-cast-1.
(c-forward-decl-or-cast-1): Invoke the new macro twice, in CASE 16 (new) and
CASE 17.5 (the source of the macro).  In CASE 16, additionally set
unsafe-maybe when appropriate.