Enabling thread independent JNI objects

This submit includes the following changes:
1.Removes the restrictions that JNI objects can be used in the created
thread only.
2. SQL_EXEC_SwithContext CLI now manages the tidList_ correctly in the
CliGlobals structure.
3. ContextCli is now not associated with a thread.

This should further improve the thread safe concept in the trafodion engine.
This would possibly improve the robustness of mysql front-end to trafodion.
This change is also required to share CmpContext across multiple sessions in
future.

Change-Id: I57d61067f05ad7747159ca8eeede905a27a03c10
Merge "Enabling thread independent JNI objects"