[Android] Fix crash in receiver.

[YorkShen]

Brief Description of the PR

Fix the following crash

java.lang.IllegalArgumentException: Receiver not registered: com.taobao.weex.WXGlobalEventReceiver@df9ef3f
	at android.app.LoadedApk.forgetReceiverDispatcher(LoadedApk.java:1095)
	at android.app.ContextImpl.unregisterReceiver(ContextImpl.java:1500)
	at android.content.ContextWrapper.unregisterReceiver(ContextWrapper.java:608)
	at com.taobao.weex.WXSDKInstance.destroy(WXSDKInstance.java:1832)
	at com.taobao.weex.WXSDKInstance.onActivityDestroy(WXSDKInstance.java:1457)

Checklist

• Demo:
• Documentation:

[weex-bot]

	Warnings
⚠️	No Changelog changes! - Can you add a Changelog? To do so,append your changes to the changelog.md
⚠️	Current pr not bind the milestone
⚠️	If your PR is about fixing a bug excluding crash the code,you should add the demo link in the PR description. Demo link: http://dotwe.org/vue
⚠️	If you update the code, maybe you should update the documentation and add the documentation link in the PR description. here is the guide about how to contribute documentation: https://github.com/apache/incubator-weex/blob/master/CONTRIBUTING.md#contribute-code-or-document

	Messages
📖	danger test finished.

Generated by 🚫 dangerJS against 6f3c67e

[lucky-chen]

ok

[lucky-chen]

add bool val onActivityCreate. then

onActivityCreate(){
 hasRegister = true;
}

and

if(hasRegister){
   getContext().unregisterReceiver(mGlobalEventReceiver);

}