[PATCH] irq code: Add coherence test for PREEMPT_ACTIVE

[PATCH] irq code: Add coherence test for PREEMPT_ACTIVE

After porting this fixlet to UML:

http://linux.bkbits.net:8080/linux-2.5/cset@41791ab52lfMuF2i3V-eTIGRBbDYKQ

, I've also added a warning which should refuse compilation with insane values
for PREEMPT_ACTIVE...  maybe we should simply move PREEMPT_ACTIVE out of
architectures using GENERIC_IRQS.

Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>