fix GradientClipByGlobalNorm. test=develop

doc/fluid/api_cn/clip_cn/GradientClipByGlobalNorm_cn.rst

@@ -58,8 +58,8 @@ GradientClipByGlobalNorm
         #   return Parameter.name=="fc_0.w_0"
         # clip = fluid.clip.GradientClipByGlobalNorm(clip_norm=1.0, need_clip=fileter_func)
 
-        sgd_optimizer = fluid.optimizer.SGDOptimizer(learning_rate=0.1)
-        sgd_optimizer.minimize(loss, grad_clip=clip)
+        sgd_optimizer = fluid.optimizer.SGDOptimizer(learning_rate=0.1, grad_clip=clip)
+        sgd_optimizer.minimize(loss)
 
     place = fluid.CPUPlace()
     exe = fluid.Executor(place)
@@ -95,5 +95,5 @@ GradientClipByGlobalNorm
         # clip = fluid.clip.GradientClipByGlobalNorm(clip_norm=1.0, need_clip=fileter_func)
 
         sgd_optimizer = fluid.optimizer.SGD(
-        learning_rate=0.1, parameter_list=linear.parameters())
-        sgd_optimizer.minimize(loss, grad_clip=clip)
\ No newline at end of file
+        learning_rate=0.1, parameter_list=linear.parameters(), grad_clip=clip)
+        sgd_optimizer.minimize(loss)