Clozure common lisp support

Hello,

I recently had to switch from buildapp to cl-launch on a project which needed to be buildable with both SBCL and CCL.  I found cl-launch baroque, hard to use and impossible to customize, so now that crunch time for that project is over, I've added CCL support to buildapp so that I will hopefully never have to use cl-launch again.  I hope you find these patches acceptable and merge them into buildapp.

The first patch make all of the changes required to load compile and build buildapp with CCL, and the second updates the Makefile so that CCL may be used by setting LISP=ccl.  If you like I would be happy to submit another patch updating the documentation to reflect that Clozure is also now supported.

Cheers,