Compile DB2 plugin for Qt on Linux

Steps:
- get Qt from Nokia's page
- install it
- run configure like this:

./configure -plugin-sql-db2 -v -I /opt/ibm/db2/V9.7/include -L /opt/ibm/db2/V9.7/lib64/
make
make install (if you want to install it)

- this should compile DB2 plugin for Qt. Now you can use this installation or copy generated Qt db2 plugin (libsqldb2.so) to /usr/lib/qt4/plugins/sqldrivers