Do not explicitly delete OpenGL shaders in VideoRendererGui.

This is handled by Android itself and may result in GL errors
when trying to release shaders when Activity is destroyed.

R=wzh@webrtc.org

Review URL: https://codereview.webrtc.org/1322703004 .

Cr-Commit-Position: refs/heads/master@{#9811}

talk/app/webrtc/java/android/org/webrtc/VideoRendererGui.java

@@ -460,9 +460,6 @@ public class VideoRendererGui implements GLSurfaceView.Renderer {
         yuvImageRenderer.release();
       }
       instance.yuvImageRenderers.clear();
-      if (instance.drawer != null) {
-        instance.drawer.release();
-      }
     }
     instance.surface = null;
     eglContext = null;