Useless test in gen_binary

[Richard Kenner]

    Would it be ok if I killed the hunk in combine.c as part of removing
    gen_binary?

I don't see it as a "useless test".  It's best to keep an expression with a
CLOBBER as simple as possible, which is why I left that there even though
it wasn't "needed".  The issue is to avoid generating useless RTL.

Of course, if you're replacing it with something that does the same
thing elsewhere, that's fine.