Need to load all the PO files for a locale

Evergreen master / and all previous versions with web client

When configuring locales for the catalog and web client, we specify them in the separate Locations of eg_vhost.conf. One is /eg/ (which is where the catalog is) and /eg/staff/ (for the web client).

So for example, it would look something like:

<LocationMatch /eg/>
...
    PerlAddVar OILSWebLocale "fr_ca"
    PerlAddVar OILSWebLocale "/openils/var/data/locale/opac/fr-CA.po"
...
</LocationMatch>

<LocationMatch /eg/staff/>
...
    PerlAddVar OILSWebLocale "fr_ca"
    PerlAddVar OILSWebLocale "/openils/var/data/locale/staff/fr-CA.po"
...
</LocationMatch>

The problem manifests where only one of the PO files gets loaded up for the locale, and so either you end up with only opac strings (missing most of the menu translations and web client functionality, etc.), or you get only the webstaff strings (which leads to an untranslated catalog search in the web client and broken catalog views for cataloging).

Talking to berick on IRC, we isolated the problem to this line in Open-ILS/src/perlmods/lib/OpenILS/WWW/EGWeb.pm's load_locale_handlers() function (around line 387):

    next if grep { $_ eq $tag } keys %registered_locales;

Commenting out this line allowed us to load more than one PO file to the locale and appeared to fix the loading issue on one of our test servers.

Reporting this bug separately from when it was uncovered in bug 1629078. Fixing this issue would be considered critical to having functional i18n for the web client.