x86/hyperv: Make hv_vcpu_is_preempted() visible

This function is referrenced from assembler, so it needs to be marked
visible for LTO.

Fixes: 3a025de6 ("x86/hyperv: Enable PV qspinlock for Hyper-V")
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Yi Sun <yi.y.sun@linux.intel.com>
Cc: kys@microsoft.com
Cc: haiyangz@microsoft.com
Link: https://lkml.kernel.org/r/20190330004743.29541-6-andi@firstfloor.org

arch/x86/hyperv/hv_spinlock.c

@@ -56,7 +56,7 @@ static void hv_qlock_wait(u8 *byte, u8 val)
 /*
  * Hyper-V does not support this so far.
  */
-bool hv_vcpu_is_preempted(int vcpu)
+__visible bool hv_vcpu_is_preempted(int vcpu)
 {
 	return false;
 }