Remove test.chap8j from BROKEN_TESTS when SCHEME is bigloo.

This test is now working with bigloo. Not sure if I was mistaken about
it being broken in bigloo, or if some other change inadvertently fixed
it.
Remove the tmp.test.chap8j target.

Compiling the a.out file doesn't take long on a modernish machine, so
tmp.test.chap8j has outlived it's usefulness.