Update Open-MPI to version 1.4.2

Some Mac-Specific issues noted in the Open-MPI changelog:

  http://www.open-mpi.org/community/lists/announce/2010/05/0037.php

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

Formula/open-mpi.rb

@@ -1,9 +1,9 @@
 require 'formula'
 
 class OpenMpi <Formula
-  url 'http://www.open-mpi.org/software/ompi/v1.4/downloads/openmpi-1.4.1.tar.gz'
+  url 'http://www.open-mpi.org/software/ompi/v1.4/downloads/openmpi-1.4.2.tar.gz'
   homepage 'www.open-mpi.org'
-  md5 'a6f87bf31b20206a9ccd4a76608f89d4'
+  md5 'e4f58c7e6792e4549424cb0420eb8655'
 
   def install
     # Compiler complains about link compatibility with FORTRAN otherwise