Fix for incorrect handling of BUFSIZE = 0. The handling of aggregations was

Fix for incorrect handling of BUFSIZE = 0.  The handling of aggregations was
flawed in that even without any ECBs with aggregation, the code logic was
assuming there was at least one aggregation (the sentinel in the IDR).  The
handling of the aggregations IDR in the DTrace state has been updated to use
an explicit counter because the IDR functionality does not provide us with an
API function to determine the amount of elements in the IDR.

Signed-off-by: Kris Van Hees <kris.van.hees@oracle.com>