Migrate to pcre2 (FTBFS on Debian 13)

[mdavidsaver]

It looks like Debian 13 dropped libpcre3-dev. So pcre.h is no longer provided by any package.

In file included from ../gateAsCa.cc:16:
../gateAs.h:49:10: fatal error: pcre.h: No such file or directory
   49 | #include <pcre.h>
      |          ^~~~~~~~

[mdavidsaver]

I guess the obvious (only?) migration path is towards pcre2.h (from libpcre2-dev)?

[ralphlange]

StreamDevice already has a ticket for that (paulscherrerinstitute/StreamDevice#103) - I should have seen it coming.