DEVEL15-windows-buf-scache-interlock-20080222

DEVEL15-windows-buf-scache-interlock-20080222

LICENSE MIT

Improve parallelism by using InterlockedIncrement and InterlockedDecrement
to adjust the refCount fields of cm_buf_t and cm_scache_t objects.  This
permits read locks to be used for increments and decrements but requires
a write-lock to perform any actions based upon the refCount hitting zero.

Inline cm_FidCmp to further improve performance.

Remove unused variables.

(cherry picked from commit 12c6cfd4435c5a491e613e6394fabeeed4d81447)