Increase of WITNESS_COUNT

Hello,

for some time I'm seeing "witness exhausted" message in my logs when I run 
with WITNESS enabled. I know it's nothing new but it's either the bug which 
is causing it is surviving for long time or there's something special in my 
setups or that it's just normal (as more code get fine grained locking more 
witnesses are used).

What are the consequences of increasing WITNESS_COUNT in 
src/sys/kern/subr_witness.c? I don't see any ill effects and I don't get the 
dreaded "witness exhausted" message. Can it be increased by default?

Thanks.

-- 
Michal Mertl