blahtexml: add --only-blahtex option

Signed-off-by: Adam Vandenberg <flangy@gmail.com>

Formula/blahtexml.rb

@@ -5,10 +5,19 @@ class Blahtexml < Formula
   url 'http://gva.noekeon.org/blahtexml/blahtexml-0.9-src.tar.gz'
   md5 'ed790599223c2f8f6d205be8988882de'
 
-  depends_on 'xerces-c'
+  depends_on 'xerces-c' unless ARGV.include? '--blahtex-only'
+
+  def options
+    [['--blahtex-only', "Build only blahtex, not blahtexml"]]
+  end
+
 
   def install
-    system "make blahtex-mac blahtexml-mac"
-    bin.install 'blahtex', 'blahtexml'
+    system "make blahtex-mac"
+    bin.install 'blahtex'
+    unless ARGV.include? '--blahtex-only'
+      system "make blahtexml-mac"
+      bin.install 'blahtexml'
+    end
   end
 end