Relax tolerance for float16 in unary_math_function_unittest
Relax tolerance for float16 in unary_math_function_unittest

hvy/chainer,wkentaro/chainer,pfnet/chainer,hvy/chainer,chainer/chainer,okuta/chainer,wkentaro/chainer,chainer/chainer,niboshi/chainer,chainer/chainer,keisuke-umezawa/chainer,niboshi/chainer,hvy/chainer,hvy/chainer,okuta/chainer,keisuke-umezawa/chainer,okuta/chainer,niboshi/chainer,tkerola/chainer,okuta/chainer,wkentaro/chainer,keisuke-umezawa/chainer,keisuke-umezawa/chainer,wkentaro/chainer,chainer/chainer,niboshi/chainer