DRTVWR-476: Add diagnostic output to llviewerjoystick.cpp.

Add ndof_dump_list() call, to enumerate available devices, when
ndof_init_first() returns failure.

Add "joystick" tags to existing LL_INFOS() (etc.) calls in
llviewerjoystick.cpp to make it easier to enable and disable such log
messages.

Add a specialized operator<<() function to log the contents of an NDOF_Device
struct. Add a couple LL_DEBUGS() calls for more visibility into library
operations.