cairo: fix build with gcc-15 on host

cairo: fix build with gcc-15 on host

* backports from 1.18.2 used since:
  https://git.openembedded.org/openembedded-core/commit/?id=070d79c8adec7e0a8862019cf61910a59b18613a

* fixes build on hosts with gcc-15 (e.g. ubuntu-25.10)

../cairo-1.18.0/test/pdiff/pdiff.h:22:13: error: â\80\98boolâ\80\99 cannot be defined via â\80\98typedefâ\80\99
   22 | typedef int bool;
      |             ^~~~
../cairo-1.18.0/test/pdiff/pdiff.h:22:13: note: â\80\98boolâ\80\99 is a keyword with â\80\98-std=c23â\80\99 onwards
../cairo-1.18.0/test/pdiff/pdiff.h:22:1: warning: useless type name in empty declaration
   22 | typedef int bool;
      | ^~~~~~~

Signed-off-by: Martin Jansa <martin.jansa@gmail.com>
Signed-off-by: Steve Sakoman <steve@sakoman.com>