i386/cpu: make -cpu host support monitor/mwait

When guest CPU PM is enabled, and with -cpu host, expose the host CPU
MWAIT leaf in the CPUID so guest can make good PM decisions.

Note: the result is 100% CPU utilization reported by host as host
no longer knows that the CPU is halted.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Eduardo Habkost <ehabkost@redhat.com>
Message-Id: <20180622192148.178309-3-mst@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
diff --git a/accel/tcg/user-exec-stub.c b/accel/tcg/user-exec-stub.c
index dbcf1ad..a32b449 100644
--- a/accel/tcg/user-exec-stub.c
+++ b/accel/tcg/user-exec-stub.c
@@ -2,6 +2,9 @@
 #include "qemu-common.h"
 #include "qom/cpu.h"
 #include "sysemu/replay.h"
+#include "sysemu/sysemu.h"
+
+bool enable_cpu_pm = false;
 
 void cpu_resume(CPUState *cpu)
 {