x86: UV, SGI RTC: add generic system vector

This patch allocates a system interrupt vector for various platform
specific uses.

Signed-off-by: Dimitri Sivanich <sivanich@sgi.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: john stultz <johnstul@us.ibm.com>
LKML-Reference: <20090304185605.GA24419@sgi.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/arch/x86/include/asm/hw_irq.h b/arch/x86/include/asm/hw_irq.h
index 370e1c8..b762ea4 100644
--- a/arch/x86/include/asm/hw_irq.h
+++ b/arch/x86/include/asm/hw_irq.h
@@ -27,6 +27,7 @@
 
 /* Interrupt handlers registered during init_IRQ */
 extern void apic_timer_interrupt(void);
+extern void generic_interrupt(void);
 extern void error_interrupt(void);
 extern void spurious_interrupt(void);
 extern void thermal_interrupt(void);