Fix table tuple accurate size calculation.
Fix table tuple accurate size calculation.

Handle NULL varchar and varbinary columns correctly in the size
calculation.

Change-Id: Ib14a40e5706b09c81f1d19b2ffef2c1b1f873935

deerwalk/voltdb,simonzhangsm/voltdb,paulmartel/voltdb,migue/voltdb,paulmartel/voltdb,deerwalk/voltdb,VoltDB/voltdb,paulmartel/voltdb,simonzhangsm/voltdb,migue/voltdb,simonzhangsm/voltdb,VoltDB/voltdb,paulmartel/voltdb,VoltDB/voltdb,paulmartel/voltdb,simonzhangsm/voltdb,VoltDB/voltdb,VoltDB/voltdb,deerwalk/voltdb,migue/voltdb,migue/voltdb,deerwalk/voltdb,VoltDB/voltdb,simonzhangsm/voltdb,paulmartel/voltdb,simonzhangsm/voltdb,paulmartel/voltdb,migue/voltdb,VoltDB/voltdb,deerwalk/voltdb,deerwalk/voltdb,migue/voltdb,simonzhangsm/voltdb,paulmartel/voltdb,simonzhangsm/voltdb,deerwalk/voltdb,deerwalk/voltdb,migue/voltdb,migue/voltdb