kvm: Provide kvm_vcpu_eligible_for_directed_yield() stub

Commit 7940876e1330671708186ac3386aa521ffb5c182 ("kvm: make local
functions static") broke KVM PPC builds due to removing (rather than
moving) the stub version of kvm_vcpu_eligible_for_directed_yield().

This patch reintroduces it.

Signed-off-by: Scott Wood <[e-mail]>
Cc: Stephen Hemminger <[e-mail]>
Cc: Alexander Graf <[e-mail]>
[Move the #ifdef inside the function. - Paolo]
Signed-off-by: Paolo Bonzini <[e-mail]>

virt/kvm/kvm_main.c

···
 }
 EXPORT_SYMBOL_GPL(kvm_vcpu_yield_to);
 
-#ifdef CONFIG_HAVE_KVM_CPU_RELAX_INTERCEPT
 /*
  * Helper that checks whether a VCPU is eligible for directed yield.
  * Most eligible candidate to yield is decided by following heuristics:
···
  */
 static bool kvm_vcpu_eligible_for_directed_yield(struct kvm_vcpu *vcpu)
 {
+#ifdef CONFIG_HAVE_KVM_CPU_RELAX_INTERCEPT
 	bool eligible;
 
 	eligible = !vcpu->spin_loop.in_spin_loop ||
···
 		kvm_vcpu_set_dy_eligible(vcpu, !vcpu->spin_loop.dy_eligible);
 
 	return eligible;
-}
+#else
+	return true;
 #endif
+}
 
 void kvm_vcpu_on_spin(struct kvm_vcpu *me)
 {