ports/78286: [PATCH] Add support for multilang for www/firefox

[Michael Johnson]

If we commit this we need to make a knob in mozconfig.in to not enable 
"ac_add_options --enable-official-branding"
if LANG_PKGNAME is defined. Or we need to get
permission from the locale mozilla team.

http://www.mozilla.org/foundation/trademarks/l10n-policy.html

Michael