问题描述：离线人脸识别demo在注册人脸时选择自动检测，进入OrbbecProLivenessDetectActivity，识别成功后退出页面，在onDisconnect()中调用mUVCCamera.stopPreview();闪退。

            以上情况在OrbbecProVideoIdentifyActivity的onDisconnect()中调用mUVCCamera.stopPreview()同样出现。

活体检测设置：RGB+Depth活体   

摄像头：奥比中光AstraPro   

特征：生活照模式   

错误信息：

at com.serenegiant.usb.UVCCamera.nativeStopPreview(Native method)
11-14 02:10:04.351 2873-3630/com.baidu.idl.face.demo A/art: art/runtime/runtime.cc:422] at com.serenegiant.usb.UVCCamera.stopPreview(UVCCamera.java:429)
11-14 02:10:04.351 2873-3630/com.baidu.idl.face.demo A/art: art/runtime/runtime.cc:422] - locked <0x09745fc3> (a com.serenegiant.usb.UVCCamera)
11-14 02:10:04.351 2873-3630/com.baidu.idl.face.demo A/art: art/runtime/runtime.cc:422] at com.baidu.aip.ofr.OrbbecProLivenessDetectActivity$2.onDisconnect(OrbbecProLivenessDetectActivity.java:311)
11-14 02:10:04.351 2873-3630/com.baidu.idl.face.demo A/art: art/runtime/runtime.cc:422] at com.serenegiant.usb.USBMonitor$UsbControlBlock.close(USBMonitor.java:1313)
11-14 02:10:04.351 2873-3630/com.baidu.idl.face.demo A/art: art/runtime/runtime.cc:422] at com.serenegiant.usb.USBMonitor.destroy(USBMonitor.java:144)
11-14 02:10:04.351 2873-3630/com.baidu.idl.face.demo A/art: art/runtime/runtime.cc:422] at com.baidu.aip.ofr.OrbbecProLivenessDetectActivity.onStop(OrbbecProLivenessDetectActivity.java:200)
11-14 02:10:04.351 2873-3630/com.baidu.idl.face.demo A/art: art/runtime/runtime.cc:422] at android.app.Instrumentation.callActivityOnStop(Instrumentation.java:1289)
11-14 02:10:04.351 2873-3630/com.baidu.idl.face.demo A/art: art/runtime/runtime.cc:422] at android.app.Activity.performStop(Activity.java:6884)
11-14 02:10:04.351 2873-3630/com.baidu.idl.face.demo A/art: art/runtime/runtime.cc:422] at android.app.ActivityThread.performDestroyActivity(ActivityThread.java:4161)
11-14 02:10:04.351 2873-3630/com.baidu.idl.face.demo A/art: art/runtime/runtime.cc:422] at android.app.ActivityThread.handleDestroyActivity(ActivityThread.java:4222)
11-14 02:10:04.351 2873-3630/com.baidu.idl.face.demo A/art: art/runtime/runtime.cc:422] at android.app.ActivityThread.-wrap6(ActivityThread.java:-1)
11-14 02:10:04.351 2873-3630/com.baidu.idl.face.demo A/art: art/runtime/runtime.cc:422] at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1539)
11-14 02:10:04.351 2873-3630/com.baidu.idl.face.demo A/art: art/runtime/runtime.cc:422] at android.os.Handler.dispatchMessage(Handler.java:102)
11-14 02:10:04.351 2873-3630/com.baidu.idl.face.demo A/art: art/runtime/runtime.cc:422] at android.os.Looper.loop(Looper.java:154)
11-14 02:10:04.351 2873-3630/com.baidu.idl.face.demo A/art: art/runtime/runtime.cc:422] at android.app.ActivityThread.main(ActivityThread.java:6121)
11-14 02:10:04.351 2873-3630/com.baidu.idl.face.demo A/art: art/runtime/runtime.cc:422] at java.lang.reflect.Method.invoke!(Native method)
11-14 02:10:04.351 2873-3630/com.baidu.idl.face.demo A/art: art/runtime/runtime.cc:422] at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:912)
11-14 02:10:04.351 2873-3630/com.baidu.idl.face.demo A/art: art/runtime/runtime.cc:422] at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:802)