title: Crash when using ConstraintLayout in Notification
body: <p>I get an <code>InflationException</code> when I use a <code>ConstraintLayout</code> in a custom <code>Notification</code>. I can use them elsewhere in my app, just not in a custom layout for a <code>Notification</code>. I'm assuming that any widget contained in a support library simply can't be used in a <code>RemoteView</code>, but I can't find any confirmation on that. Does anybody know?</p>
  
  <pre><code>E/StatusBar: couldn't inflate view for notification com.example.app/0x1
  android.view.InflateException: Binary XML file line #2: Binary XML file line #2: Error inflating class android.support.constraint.ConstraintLayout
  Caused by: android.view.InflateException: Binary XML file line #2: Error inflating class android.support.constraint.ConstraintLayout
  Caused by: java.lang.ClassNotFoundException: Didn't find class "android.support.constraint.ConstraintLayout" on path: DexPathList[[],nativeLibraryDirectories=[/system/priv-app/TeleService/lib/arm64, /system/fake-libs64, /system/priv-app/TeleService/TeleService.apk!/lib/arm64-v8a, /system/lib64, /vendor/lib64, /system/lib64, /vendor/lib64]]
      at dalvik.system.BaseDexClassLoader.findClass(BaseDexClassLoader.java:93)
      at java.lang.ClassLoader.loadClass(ClassLoader.java:379)
      at java.lang.ClassLoader.loadClass(ClassLoader.java:312)
      at android.view.LayoutInflater.createView(LayoutInflater.java:606)
      at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:790)
      at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:730)
      at android.view.LayoutInflater.inflate(LayoutInflater.java:492)
      at android.view.LayoutInflater.inflate(LayoutInflater.java:423)
      at android.widget.RemoteViews.inflateView(RemoteViews.java:3278)
      at android.widget.RemoteViews.-wrap1(Unknown Source:0)
      at android.widget.RemoteViews$AsyncApplyTask.doInBackground(RemoteViews.java:3380)
      at android.widget.RemoteViews$AsyncApplyTask.doInBackground(RemoteViews.java:3376)
      at android.os.AsyncTask$2.call(AsyncTask.java:333)
      at java.util.concurrent.FutureTask.run(FutureTask.java:266)
      at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1162)
      at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:636)
      at java.lang.Thread.run(Thread.java:764)
  E/AndroidRuntime: FATAL EXCEPTION: main
  Process: com.example.app, PID: 9732
  android.app.RemoteServiceException: Bad notification posted from package com.example.app: Couldn't inflate contentViewsandroid.view.InflateException: Binary XML file line #2: Binary XML file line #2: Error inflating class android.support.constraint.ConstraintLayout
      at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1775)
      at android.os.Handler.dispatchMessage(Handler.java:105)
      at android.os.Looper.loop(Looper.java:164)
      at android.app.ActivityThread.main(ActivityThread.java:6541)
      at java.lang.reflect.Method.invoke(Native Method)
      at com.android.internal.os.Zygote$MethodAndArgsCaller.run(Zygote.java:240)
      at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:767)
  </code></pre>