boost-build 1.55.0

This formula is updated to get boost-build from the git repository.
Changes to boost-build have been made but the reported version has
not changed. Thus the version is also changed to match the boost
one.

Closes Homebrew/homebrew#26849.

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

Formula/boost-build.rb

@@ -2,18 +2,17 @@ require 'formula'
 
 class BoostBuild < Formula
   homepage 'http://boost.org/boost-build2/'
-  url 'http://downloads.sourceforge.net/project/boost/boost/1.53.0/boost_1_53_0.tar.bz2'
-  sha1 'e6dd1b62ceed0a51add3dda6f3fc3ce0f636a7f3'
-  version '2011.12-svn'
+  url 'http://github.com/boostorg/build/archive/boost-1.55.0.tar.gz'
+  sha1 '9daf7587b017716ffd164bcf11d82c4ac00c8ca0'
 
-  head 'http://svn.boost.org/svn/boost/trunk/tools/build/v2/'
+  head 'https://github.com/boostorg/build.git'
 
   def install
     if build.head?
       system "./bootstrap.sh"
       system "./b2", "--prefix=#{prefix}", "install"
     else
-      cd 'tools/build/v2' do
+      cd 'v2' do
         system "./bootstrap.sh"
         system "./b2", "--prefix=#{prefix}", "install"
       end