Add a locale fact which uses eselect locale to retrieve system default

lib/facter/locale.rb

@@ -0,0 +1,7 @@
+Facter.add(:locale) do
+    confine :osfamily => :gentoo
+    setcode do
+      Facter::Core::Execution.exec('eselect --colour=no --brief locale show').strip
+    end
+end
+