xmlformat: use perl version

Since Ruby 2 the ruby version issues many syntax warnings and OSX ships also
with Ruby >2. Fortunately there is a Perl version on the same archive that
does exactly the same thing. OSX ships with Perl 5, so we're fine.

Closes Homebrew/homebrew#30411.

Signed-off-by: Mike McQuaid <mike@mikemcquaid.com>

Formula/xmlformat.rb

@@ -6,6 +6,6 @@ class Xmlformat < Formula
   sha1 '405057df0b8160775d486b671348820359b4b85d'
 
   def install
-    bin.install "xmlformat.rb" => "xmlformat"
+    bin.install "xmlformat.pl" => "xmlformat"
   end
 end