Following tries to close a number of random discussions that noticed 
that the GDB module contains stuff that is no longer applicable.

The attached modifies GDB's "gdb" CVS module trimming it back to what is 
currently relevant.  It drops mmalloc/ (not used), cgen/cpu/ (moved to 
cpu/), intl (use installed), and utils/ (not used).

It also adds the module old-gdb which retains all the old directories 
and hence can be used to check out old gdb versions (although "gdb" will 
be sufficient for most needs).

I'll look to commit this in a week, this needs to be closed before 6.3 
is branched.

Andrew