MFC 208912: Fix a sign bug that caused adaptive spinning in sx_xlock() to not work properly.
MFC 208912:
Fix a sign bug that caused adaptive spinning in sx_xlock() to not work
properly.

Approved by:	re (bz)

jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase