count-delta.c: comment fixes
count-delta.c: comment fixes

There was a stale comment that explains why the old code could
undercount when delta data copied things around inside detination
buffer.  We do not use that kind of delta, so the comment does
not apply.

destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git