qemu: Set govmmQemu NoReboot config Knob

The Kata architecture does not support rebooting VMs (the lifecycle
being start/exec/kill) and if a VM is killed (e.g. using sysrq-trigger),
the VM does not exit fully and other layers do not notice the state change.
Set the NoReboot config Knob so that govmmQemu.LaunchQemu() runs QEMU
with the --no-reboot command-line option.

Fixes: #2866

Signed-off-by: Liam Merwick <liam.merwick@oracle.com>

src/runtime/virtcontainers/qemu.go

@@ -481,6 +481,7 @@ func (q *qemu) createSandbox(ctx context.Context, id string, networkNS NetworkNa
 		NoUserConfig: true,
 		NoDefaults:   true,
 		NoGraphic:    true,
+		NoReboot:     true,
 		Daemonize:    true,
 		MemPrealloc:  q.config.MemPrealloc,
 		HugePages:    q.config.HugePages,

src/runtime/virtcontainers/qemu_test.go

@@ -202,6 +202,7 @@ func TestQemuKnobs(t *testing.T) {
 	assert.Equal(q.qemuConfig.Knobs.NoUserConfig, true)
 	assert.Equal(q.qemuConfig.Knobs.NoDefaults, true)
 	assert.Equal(q.qemuConfig.Knobs.NoGraphic, true)
+	assert.Equal(q.qemuConfig.Knobs.NoReboot, true)
 }
 
 func testQemuAddDevice(t *testing.T, devInfo interface{}, devType deviceType, expected []govmmQemu.Device) {