Created by: songyouwei

dygraph.PRelu Python API类型检查增强 当此动态图API在静态图下运行时：

检查input类型是否为Variable 检查数据类型是否为float32 异常情况示例如下:

import paddle.fluid as fluid
import numpy as np
layer = fluid.PRelu(
    mode='all',
    param_attr=fluid.ParamAttr(
        initializer=fluid.initializer.Constant(1.0)))
# the input must be Variable.
x0 = fluid.create_lod_tensor(
    np.array([-1, 3, 5, 5]), [[1, 1, 1, 1]], fluid.CPUPlace())
layer(x0)
# TypeError: The type of 'input' in PRelu must be <class 'paddle.fluid.framework.Variable'>, but received <class 'paddle.fluid.core_avx.LoDTensor'>. 

data_t = fluid.data(name="input", shape=[5, 200, 100, 100], dtype="float64")
layer(data_t)
# TypeError: The data type of 'input' in PRelu must be ['float32'], but received float64.