abstract C++ ABI dependencies

[Anthony Green]

Jim wrote in gdb/jv-typeprint.c:
> ! 		  is_full_physname_constructor =
> is_constructor_name (physname) != 0 || is_destructor_name (physname) != 0;

Actually, it didn't look exactly like that.  My mailer is munging it because
it was too long.  The patch is fine by me as long as the formatting is
changed.

I also find "is_constructor_name (physname) || is_destructor_name
(physname)" easier to read, but to each his own...

Thanks!

AG