x86: provide a native_init_IRQ function on 64-bit

x86_64 lacks a native_init_IRQ() function, so we turn the arch's
init_IRQ() function into a native construct
Signed-off-by: Glauber de Oliveira Costa <gcosta@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

arch/x86/kernel/i8259_64.c

@@ -456,7 +456,9 @@ void __init init_ISA_irqs (void)
 	}
 }
 
-void __init init_IRQ(void)
+void init_IRQ(void) __attribute__((weak, alias("native_init_IRQ")));
+
+void __init native_init_IRQ(void)
 {
 	int i;
 

include/asm-x86/hw_irq_64.h

@@ -141,6 +141,7 @@ extern void print_IO_APIC(void);
 extern int IO_APIC_get_PCI_irq_vector(int bus, int slot, int fn);
 extern void send_IPI(int dest, int vector);
 extern void setup_ioapic_dest(void);
+extern void native_init_IRQ(void);
 
 extern unsigned long io_apic_irqs;