Fixing some build issue on OSX

Hi Paulo

I have commit a fix that cause some bug at build time. You can found the commit to merge here:
https://github.com/mathk/smalltalk/commit/1fa5efe01f

The issue was that the environ global was remove from libc on osx and replace by the _NSGetEnviron.
I have only be able to test on 10.7. So I have no idea if that is compatible with 10.6

Also the MessgaeLookup.st file was missing in the kernel package.xml

Thanks in advance

--
Mathieu