Common Lisp misidentified as OpenCL

Common Lisp code using the .cl extension is misidentified as OpenCL:
http://github.com/search?q=extension%3A.cl+defun

This request adds .cl as a Common Lisp extension, and also two samples.

Tested with:
http://github.com/franzinc/imap
http://github.com/bempp/bempp (the .cl files in lib/fiber/CL)
http://github.com/skelcl/skelcl (the .cl files in include/SkelCL/detail and examples/mandelbrot)