cmpbyt was returning 2 to report both an error in the way it is
called (wrong number of command-line arguments) and the fact that
its two arguments are different programs. This patch fixes this and makes
cmpbyt's behaviour similar to the one of the cmp Unix command, i.e.
returning 0 to report file similarity, 1 to report file difference
and 2 for real errors.
The stripping is done during bootstrap, when copying the new ocamlc, ocamllex and ocamldep to boot/. The new "stripdebug" tool performs this task.
As a consequence, comparing the new compilers with the boot/ compilers at the end of bootstrap is more complicated, since the debug section must be ignored. A new tool, "cmpbyt" in tools/, performs this comparison.