PR modula2/108344 disable default opening of /dev/tty

This patch changes removes the static initialisation code for KeyBoardLEDs.cc.
The module is only initialised if one of the exported functions is called.
This is useful as the module will access /dev/tty which might not be
available.  TimerHandler.mod has also been changed to disable the scroll
lock LED as a sign of life.

gcc/m2/ChangeLog:

	PR modula2/108344
	* gm2-libs-coroutines/TimerHandler.mod (EnableLED): New constant.
	(Timer): Test EnableLED before switching on the scroll LED.

libgm2/ChangeLog:

	PR modula2/108344
	* libm2cor/KeyBoardLEDs.cc (initialize_module): New function.
	(SwitchScroll): Call initialize_module.
	(SwitchNum): Call initialize_module.
	(SwitchCaps): Call initialize_module.
	(SwitchLEDs): Call initialize_module.
	(M2EXPORT): Remove initialization code.

Signed-off-by: Gaius Mulley <gaiusmod2@gmail.com>