Fix mac bug where luascript.luac wasn't building

SContruct was modified to run both builders, one for lua and another for
xsdb. BuildUtil accommodates running both builders. We needed to
seperate the builders because otherwise the luascript.o would be in the
list of files to be linked in xsdb, which is not what we want for the
mac version.
Merge branch 'json_tests' of github.com

Conflicts:
	site_scons/BuildUtil.py