accel/kvm: Make kvm_has_guest_debug static

This variable is not used or declared outside kvm-all.c.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Gavin Shan <gshan@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Tested-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

accel/kvm/kvm-all.c

@@ -98,7 +98,7 @@ bool kvm_allowed;
 bool kvm_readonly_mem_allowed;
 bool kvm_vm_attributes_allowed;
 bool kvm_msi_use_devid;
-bool kvm_has_guest_debug;
+static bool kvm_has_guest_debug;
 static int kvm_sstep_flags;
 static bool kvm_immediate_exit;
 static hwaddr kvm_max_slot_size = ~0;