1.0.5.39: sb-sprof call counting

1.0.5.39: sb-sprof call counting

         * Add support for deterministically tracking the amount of times
           that certain functions were called during a sb-sprof profiling
           run.
         * The goal is to allow people to easily see whether a lot of time
           is spent in function X due to it being called often, or due to
           the average call being slow.
         * The benefit over using sb-profile is that a) the reporting
           of the call counts is integrated into the normal sb-sprof
           interface and b) there's a lot less overhead, since we're just
           counting calls, not tracking cpu usage / consing.