Fixes to common vulnerabilities found in IBM Db2 High Performance Unload

IBM DB2 High Performance Unload 6.1.0.3, 5.1.0.1, 6.1.0.2, 6.5, 6.5.0.0 IF1, 6.1.0.1, 6.1, and 5.1 could allow an authenticated user to cause the program to crash due to the incorrect calculation of the size of the data that is being pointed to.