localization does not work on Debian based distributions
On Debian/wheezy (and Ubuntu/trusty according to Dominic) the interface is always English, while working fine according to the locale settings on FreeBSD (I presume also on RH/CentOS). Might or might not be related to #7262.
fixes #9648 - only initialise text domains that have files in the dir
6786f4cf changed the domain to avoid configuring two identical text domains,
but this reverts that and instead makes the availability check more specific
by checking for the .mo files inside the dir.
This prevents /usr/share/locale being added as a domain when the .mo files
haven't been installed there.
It also only configures the first domain that is available.
refs #9648 - use correct domain for system locales, only load one domain
This reverts commit 96ee3d8cb0f0da278bac50ceb4cc15e9092e382f.