Cleanup and encapsulate IR Capture verification:

- Add accessors for setting the jtag_verify_capture_ir flag.
- Use them in handle_verify_ircapture_cpmmand
- Change variable type to bool; make it static.


git-svn-id: svn://svn.berlios.de/openocd/trunk@2164 b42882b7-edfa-0310-969c-e2dbd0fdcd60