KVM: selftests: Make monitor_mwait require MONITOR/MWAIT feature

If this feature is not supported or is disabled by IA32_MISC_ENABLE on
the host, executing MONITOR or MWAIT instruction from the guest doesn't
cause monitor/mwait VM exits, but a #UD.

So, we need to skip this test if CPUID.01H:ECX[3] is cleared.

Signed-off-by: Zide Chen <zide.chen@intel.com>
Link: https://lore.kernel.org/r/20240411210237.34646-1-zide.chen@intel.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

tools/testing/selftests/kvm/x86_64/monitor_mwait_test.c

@@ -75,6 +75,7 @@ int main(int argc, char *argv[])
 	struct ucall uc;
 	int testcase;
 
+	TEST_REQUIRE(this_cpu_has(X86_FEATURE_MWAIT));
 	TEST_REQUIRE(kvm_has_cap(KVM_CAP_DISABLE_QUIRKS2));
 
 	vm = vm_create_with_one_vcpu(&vcpu, guest_code);