gmtl: use new dsl

Formula/gmtl.rb

@@ -1,9 +1,10 @@
 require 'formula'
 
 class Gmtl < Formula
-  url 'http://downloads.sourceforge.net/project/ggt/Generic%20Math%20Template%20Library/0.6.1/gmtl-0.6.1.tar.gz'
   homepage 'http://ggt.sourceforge.net/'
+  url 'http://downloads.sourceforge.net/project/ggt/Generic%20Math%20Template%20Library/0.6.1/gmtl-0.6.1.tar.gz'
   md5 '1391af2c5ea050dda7735855ea5bb4c1'
+
   head 'https://ggt.svn.sourceforge.net/svnroot/ggt/trunk/'
 
   depends_on 'scons' => :build
@@ -12,7 +13,7 @@ class Gmtl < Formula
   # https://sourceforge.net/tracker/?func=detail&aid=3172856&group_id=43735&atid=437247
   # The SConstruct from gmtl's HEAD doesn't need to be patched
   def patches
-    DATA unless ARGV.build_head?
+    DATA unless build.head?
   end
 
   def install