[PATCH] Fix/Update misc comments

[Tom Tromey]

Luis> That's the confusing part. There is a single_step (...) function for
Luis> gdbserver linux-low, but i don't see such a function for gdb.

Luis> So this reference looks stale to me.

Hah, I jumped to the tag and saw the function existed, but forgot to
check the directory.

The patch seems fine to me.  You can check it in.
If Pedro has some suggestions, we can always put in another patch.

Tom