Do not kick vcpus in TCG mode

In TCG mode, iothread and vcpus run in lock-step. So it's pointless to
send a signal from qemu_cpu_kick to the vcpu thread - if we got here,
the receiver already left the vcpu loop.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>

cpus.c

diff --git a/cpus.c b/cpus.c
index c996ac5..b60410c 100644
--- a/cpus.c
+++ b/cpus.c
@@ -869,7 +869,7 @@
     CPUState *env = _env;
 
     qemu_cond_broadcast(env->halt_cond);
-    if (!env->thread_kicked) {
+    if (kvm_enabled() && !env->thread_kicked) {
         qemu_cpu_kick_thread(env);
         env->thread_kicked = true;
     }