More cleanup, using $(var:J) to cleanup the error messages.

svn path=/branches/boost_build_v2/boost/tools/jam/; revision=13319
A couple of minor changes for backward compatibility.

svn path=/branches/boost_build_v2/boost/tools/build/; revision=13323
Killed GLOB workaround; perforce has fixed it

svn path=/branches/boost_build_v2/boost/tools/build/; revision=13385
Improved error messages.

svn path=/branches/boost_build_v2/boost/tools/build/; revision=13392