backout 6351092: causes 6447223

[david.mar...@sun.com]

Author: dm120769
Repository: /hg/onnv/onnv-gate
Revision: 03397662655dec71c3fa01d128e37b16c6556f8c
Log message:
backout 6351092: causes 6447223

Files:
        update: usr/src/uts/common/disp/thread.c
        update: usr/src/uts/common/sys/thread.h