checkincludes.pl is more useful if it actually removed the lines.  This
adds support for that with -r.

[akpm@linux-foundation.org: improve usage message]
Signed-off-by: NLuis R. Rodriguez <lrodriguez@atheros.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NSam Ravnborg <sam@ravnborg.org>