Enable local_pool_dnn opt. It was disabled by mistake in a rebase.
Fix crash in python 3, due to difference in comprenhension list.
Fix test following fix to dnn pool opt
Make all dnn op do not check the broadcast flags.
Better hack to skip broadcast check on the GPU.
small fix following code review
Merge pull request #2307 from nouiz/dnn_pool

CRASH/OPT fix (quick to review)