fix up btrace options & manpage

fix up btrace options & manpage

The btrace script & man page didn't quite match for options,
and the btrace script was missing a few options in the getopts
specification (b&n).  Also, there seems to be no such thing as
a "summarize" option anywhere, so remove it.

Reported-by: /Milos Malik <mmalik@redhat.com <mailto:mmalik@redhat.com>>/
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>