kern/58154: Snapshots prevent disk sync on shutdown.

[Julien Gabel]

Hello,

FYI, it seems that i do not encountered this problem on my test machine
running RELENG_5 (i.e. 5.3-BETAX and now 5.3-RCX). But to be honnest,
i don't think the test machine is as busy as my FreeBSD servers and my
notebook, each running RELENG_5_2 (on which the problem appeared) nor
has the same configuration.

Nonetheless, this particularly annoying problem seems to be gone for me.
-- 
-jpeg.