[patch/testsuite/cp] exception.exp: partially refurbish

[Michael Elizabeth Chastain]

That's cool.  I would be happy to add a bunch of MacOS arms to the
gdb_test_multiple's.

My plan is to wait for Daniel Jacobowitz to finish his current large C++
project and then talk about exceptions.  I really just wanted to push
exception.exp out of the "does not even compile on hp-ux" state, not
pull it into "really test exceptions, including all the UI issues of
which command prints what" state.

Michael C