irq: Fix circular headers dependency

irq: Fix circular headers dependency

asm-generic/hardirq.h needs asm/irq.h which might include
linux/interrupt.h as in the sparc 32 case. At this point
we need irq_cpustat generic definitions, but those are
included later in asm-generic/hardirq.h.

Then delay a bit the inclusion of irq.h from
asm-generic/hardirq.h, it doesn't need to be included early.

This fixes:

 include/linux/interrupt.h: In function '__raise_softirq_irqoff':
 include/linux/interrupt.h:414: error: implicit declaration of function 'local_softirq_pending'
 include/linux/interrupt.h:414: error: lvalue required as left operand of assignment

Reported-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Koki Sanagi <sanagi.koki@jp.fujitsu.com>
Cc: mathieu.desnoyers@efficios.com
Cc: rostedt@goodmis.org
Cc: nhorman@tuxdriver.com
Cc: scott.a.mcmillan@intel.com
Cc: eric.dumazet@gmail.com
Cc: kaneshige.kenji@jp.fujitsu.com
Cc: davem@davemloft.net
Cc: izumi.taku@jp.fujitsu.com
Cc: kosaki.motohiro@jp.fujitsu.com
LKML-Reference: <20100908122557.GA5310@nowhere>
Signed-off-by: Ingo Molnar <mingo@elte.hu>