joystick:

joystick:
- only poll joysticks if we have an active joystick
- active joystick is defined as having callback and having positive (NON-ZERO!) pollInterval, as per GLUT sources
- use fgState.NumActiveJoysticks instead of fghHaveJoystick to save bunch of unnecessary function calls etc
- fghcbCheckJoystickPolls more concervative, per window we first check if a joystick is active (per above definition)

git-svn-id: svn+ssh://svn.code.sf.net/p/freeglut/code/trunk/freeglut/freeglut@1554 7f0cb862-5218-0410-a997-914c9d46530a