sysutils/lsof Author Question (for CLANG)....

Vic Abell (the lsof author) asked me the following:
In adjusting for clang I have come up with an unanswered
question.  Where is the VOP_UNLOCK() macro defined?

I've done a full search of all the files in /usr/src/sys
and can't find its definition, but I find many, many
uses.

Perhaps someone on the freebsd-current list knows.

Can someone help me help him?