fix use C as default locale.

Currently facter sets only LANG environment variable, this does not
work on systems that have LC_ALL configured, because LC_ALL
have higher priority than LANG variable.

So the correct procedure is to configure LC_ALL=C instead of LANG=C.
change resolution_spec to test LC_ALL locale environment  var.
should configure LANG and LC_ALL.

refer to the pull request:
https://github.com/puppetlabs/facter/pull/497
Merge pull request #497 from lmello/master

(#22097) This enforces using english locale before running facter commands.