Removal of xlocale.h causes weechat failure during perl plugin build as perl.h includes it

[Earnestly]

Currently when attempting to build weechat and its perl plugin I get the
following error:


In file included from /home/weechat/src/plugins/perl/weechat-perl.c:26:0:
/usr/lib/perl5/core_perl/CORE/perl.h:738:13: fatal error: xlocale.h: No such file or directory
 #   include <xlocale.h>
             ^~~~~~~~~~~
compilation terminated.

This was due to commit f0be25b6336db7492e47d2e8e72eb8af53b5506d which
removed xlocale.h which is currently included by perl:

    https://perl5.git.perl.org/perl.git/blob/HEAD:/perl.h#l738

Although this does seem to be resolved in other places by just
rebuilding perl itself:

    https://bugzilla.redhat.com/show_bug.cgi?id=1464244