sys_poll spends around 1/2 of the execution time allocating / freeing a
few bytes temporary memory.

The attached patch tries to avoid these allocation by using the stack -
usually only a few bytes are needed, kmalloc is used for the rest.

The result: one poll of stdin is down from 1736 cpu ticks to 865 cpu
ticks (Pentium II/350 SMP, SMP kernel)

select() should also be faster, but I haven't written a micro-benchmark
for select.

Please test it,

--
	Manfred