MFC of 269692, 322179, 322463, and 322464:
269692: cswitch is unsigned, so don't compare it < 0
322179: Correct ordering of bio's in gjournal queue
322463: Eliminate a variable that is set-only in g_journal.c
322464: Correct check for reads in gjournal
Submitted by: Dr. Andreas Longwitz <longwitz@incore.de>
Discussed with: kib
Approved by: re (marius)