6301220 Fix stats reporting so we do not lie about spins.

[nore...@opensolaris.org]

Author: dv142724
Repository: /hg/onnv/onnv-gate
Revision: 9b95cbd16c92190f4c7137d1f4fefb02a7be4daa
Log message:
6301220 Fix stats reporting so we do not lie about spins.

Files:
        update: usr/src/uts/common/os/mutex.c