Created by: danleifeng

PR types

Bug fixes

PR changes

APIs

Describe

fix is_empty, main changes include:

1. api interface from is_empty(x, cond=None) to is_empty(x, name=None)
2. add dygraph mode for is_empty
3. edit example code in static mode
4. add example code in dygraph mode

chinese doc PR: https://github.com/PaddlePaddle/FluidDoc/pull/2692