find the DB2 libraries that match the pointer size
fixed x_integer handling for 64-bit

DB2 (erroneously?) assumes a SQL_C_LONG is a 32-bit integer and
defines SQLINTEGER accordingly.  Since a long integer is likely 64
bits on a 64-bit platform, using 'SQLINTEGER' instead of 'long' makes
more sense.
eliminated compiler warnings
fix to allow a statement to be executed multiple times

- close the cursor if one is open
- do not clear parameter bindings between executions
report attempt to bind use elements both by position and name
provide atomic transaction support even when autocommit is enabled
a SQL_SUCCESS_WITH_INFO return code should not result in an exception
freeing a statement automatically closes the cursor and releases column buffers
added result verification and incorporated common tests into the db2 backend tests
sqlState was losing the supplied message text