util: Add virGettextInitialize, convert the code

util: Add virGettextInitialize, convert the code

Take setlocale/gettext error handling pattern from tools/virsh-*
and use it for all standalone binaries via a new shared
virGettextInitialize routine. The virsh* pattern differed slightly
from other callers. All users now consistently:

* Ignore setlocale errors. virsh has done this forever, presumably for
  good reason. This has been partially responsible for some bug reports:

  https://bugzilla.redhat.com/show_bug.cgi?id=1312688
  https://bugzilla.redhat.com/show_bug.cgi?id=1026514
  https://bugzilla.redhat.com/show_bug.cgi?id=1016158

* Report the failed function name
* Report strerror