pc: introduce a function to allocate cpu irq.

Introduce a function, pc_allocate_cpu_irq(), to allocate cpu irq
in order to make pic_irq_request() piix independent.
Later piix code will be split out to another file keeping pic_irq_request()
static.

Signed-off-by: Isaku Yamahata <yamahata@valinux.co.jp>
Acked-by: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>

hw/pc.c

diff --git a/hw/pc.c b/hw/pc.c
index c88158c..fa11477 100644
--- a/hw/pc.c
+++ b/hw/pc.c
@@ -805,6 +805,11 @@
     return env;
 }
 
+static qemu_irq *pc_allocate_cpu_irq(void)
+{
+    return qemu_allocate_irqs(pic_irq_request, NULL, 1);
+}
+
 /* PC hardware initialisation */
 static void pc_init1(ram_addr_t ram_size,
                      const char *boot_device,
@@ -928,7 +933,7 @@
         rom_add_option(option_rom[i]);
     }
 
-    cpu_irq = qemu_allocate_irqs(pic_irq_request, NULL, 1);
+    cpu_irq = pc_allocate_cpu_irq();
     i8259 = i8259_init(cpu_irq[0]);
     isa_irq_state = qemu_mallocz(sizeof(*isa_irq_state));
     isa_irq_state->i8259 = i8259;