add qlock to the list of possible cpu-yielding calls for threads in a proc.

Notes:
Mon Aug 20 17:32:34 EDT 2007 geoff
    There's more to the story, actually, so the changes
    made are more extensive.


Reference: /n/sources/patch/applied/threadman
Date: Fri Aug 10 15:41:30 CES 2007
Signed-off-by: quanstro@quanstro.net
Reviewed-by: geoff

--- /sys/man/2/thread	Fri Aug 10 15:40:01 2007
+++ /sys/man/2/thread	Fri Aug 10 15:39:57 2007
@@ -223,6 +223,7 @@
 A thread must explicitly relinquish control of the processor
 before another thread in the same proc is run.
 Calls that do this are
+.IR qlock ,
 .IR yield ,
 .IR proccreate ,
 .IR procexec ,