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 (@KIEUN MUN (kieuns)), 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.
Note to reviewers: This is a slightly tweked version of the patch by @KIEUN MUN (kieuns) posted
in a comment of T88877.
I cannot test this myself, we need to ensure that it both fixes the issue on the new OSX
version, and that it still works on the older ones.