Fix building in ISO C23

Fix building in ISO C23

ISO C23 added bool type as a keyword. It is the standard GCC 15 uses by default and
compilation of bindings/perl/solv_perl.c fails then:

    bindings/perl/solv_perl.c:1641:13: error: ‘bool’ cannot be defined via ‘typedef’
     1641 | typedef int bool;
	  |             ^~~~
    /home/test/fedora/libsolv/libsolv-0.7.31-build/libsolv-0.7.31/redhat-linux-build/bindings/perl/solv_perl.c:1641:13: note: ‘bool’ is a keyword with ‘-std=c23’ onwards
    /home/test/fedora/libsolv/libsolv-0.7.31-build/libsolv-0.7.31/redhat-linux-build/bindings/perl/solv_perl.c:1641:1: warning: useless type name in empty declaration
     1641 | typedef int bool;
	  | ^~~~~~~

The typedef comes from bindings/solv.i which attemps to supply it in case Swig
undefines it.

This patch fixes it by not defining it in case ISO C23 or newer is in
use. Keywords cannot be checked by a preprocessor, neither undefined
(by Swig).

Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=2340762