[fusion] compiled-in aperiodic mode

[Jan Kiszka]

Hi Philippe,

maybe something low-prio for your todo list: why not make the aperiodic 
timer mode also exclusive via an optional compile switch? Just like 
CONFIG_RTAI_HW_APERIODIC_TIMER decides if only periodic mode is 
available. Would save some checks in critical paths and would also 
reduce the nucleus code size a bit.

BTW, I'm still having difficulties to understand the motivation that the 
nucleus on the one hand accepts nanoseconds as time(out) values in 
periodic mode and converts them back internally but, on the other hand, 
the users are forced to transform periodic ticks to ns on their own. Did 
I ask you about this issue before? Then accept my forehanded excuse, I 
don't remember it anymore. ;)

Jan