added compiled Lisp version of primes example

The compiled version of the Lisp primes is much
faster than the interpreted version.

$ time ./run_intr.lisp
...
real    0m0.018s
user    0m0.016s
sys     0m0.000s

$ time ./run_comp.lisp
...
real    0m0.009s
user    0m0.004s
sys     0m0.004s

It is not as fast as the C version.

$ time ./primes
...
real    0m0.002s
user    0m0.000s
sys     0m0.000s