window-afsd-bad-version-20090228

window-afsd-bad-version-20090228

LICENSE MIT

create a new cpp symbol CM_SCACHE_VERSION_BAD to represent data version
values in cm_scache objects that are known to be invalid.

then consistently apply this value throughout the code.  Previously
some invalid values were set to 0 and others to -1 (0xFFFFFFFF:FFFFFFFF).

Also fix at least one location where CM_BUF_VERSION_BAD was not used.