pdns: add --HEAD

Closes Homebrew/homebrew#27114.

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

Formula/pdns.rb

@@ -1,7 +1,8 @@
 require 'formula'
 
 class Pdns < Formula
-  homepage 'http://wiki.powerdns.com'
+  homepage 'http://www.powerdns.com'
+  head 'https://github.com/powerdns/pdns.git'
   url 'http://downloads.powerdns.com/releases/pdns-3.3.1.tar.gz'
   sha1 '555862bf9635d1dcab2c4f3b7569bdd8212ef67f'
 
@@ -27,6 +28,7 @@ class Pdns < Formula
       args << "--with-modules=gsqlite3"
     end
 
+    system "./bootstrap" if build.head?
     system "./configure", *args
 
     # Compilation fails at polarssl if we skip straight to make install