Looks like OSX changed the default format of its locale, which is not
valid anymore for gettext/boost::locale.
Solution based on investigations and patch by Kieun Mun (@kieuns), with
some further tweaks by Ankit Meel (@ankitm), many thanks.
Also add an exception catcher on `std::runtime_error` in
`bl_locale_set()`, since in OSX catching the ancestor `std::exception`
does not work with `boost::locale::conv::conversion_error` and the like
for some reasons.
Reviewed By: #platform_macos, brecht
Maniphest Tasks: T88877
Differential Revision: https://developer.blender.org/D13019
be0d5da341