fix 100% cpu utilization when cpu is stopped

> Hello,
>
> d6f4ade2 (disentangle tcg and deadline calculation, 2010-03-10)
> introduces following regression(s):
>
> 100% cpu utilization when QEMU is invoked like:
> qemu -S -s ...
>
> ditto when gdb takes control over the session via gdb-stub
> (i.e. the breakpoint is hit or C-c is pressed inside gdb to
>   interrupt the attached qemu instance)

The bug is that env->stopped is not really as comprehensive as it seems to
be (and cpu_has_work thinks); it is only valid with iothread basically,
and even then it is cleared by reset and it is not set when starting
qemu with -S.
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Cc: malc <av1474@comtv.ru>
Signed-off-by: Nmalc <av1474@comtv.ru>

cpus.c

@@ -100,9 +100,7 @@ static int cpu_can_run(CPUState *env)
 {
     if (env->stop)
         return 0;
-    if (env->stopped)
-        return 0;
-    if (!vm_running)
+    if (env->stopped || !vm_running)
         return 0;
     return 1;
 }
@@ -111,7 +109,7 @@ static int cpu_has_work(CPUState *env)
 {
     if (env->stop)
         return 1;
-    if (env->stopped)
+    if (env->stopped || !vm_running)
         return 0;
     if (!env->halted)
         return 1;