Update glib and add PCRE package

* configure.ac: Add PCRE as source package.
* packages/pacakges.current (glib): Update
(pcre): New.
* src/config.nsi.in, src/inst-pcre.nsi, src/uninst-pcre.nsi,
src/inst-sections.nsi: Add new package.

This is the most recent version of glib that does not require
a new build tool integration. It compiles under Debian Bullseye
but does require PCRE so we add PCRE.

(cherry picked from commit d9c20f63bea4698f3662f309afb0b0f2b991efe4)