kvm: Enable use of kvm_irqchip_in_kernel in hwlib code

Provide a dummy kvm_kernel_irqchip so that kvm_irqchip_in_kernel can be
used by code that is not under CONFIG_KVM protection.
Signed-off-by: NJan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: NAvi Kivity <avi@redhat.com>

kvm-stub.c

@@ -18,6 +18,7 @@
 #include "kvm.h"
 
 KVMState *kvm_state;
+bool kvm_kernel_irqchip;
 
 int kvm_init_vcpu(CPUArchState *env)
 {