PERF: Speedup np.quantile.
PERF: Speedup np.quantile.

Avoiding the unnecessary calls to moveaxis() speed up
`np.quantile(x, .5)` (`x = np.random.rand(1000)`) by ~10% (although
there's a lot of variability) for me.

mattip/numpy,mattip/numpy,charris/numpy,mhvk/numpy,pdebuyl/numpy,jakirkham/numpy,charris/numpy,anntzer/numpy,endolith/numpy,pdebuyl/numpy,endolith/numpy,charris/numpy,jakirkham/numpy,jakirkham/numpy,seberg/numpy,charris/numpy,mhvk/numpy,rgommers/numpy,mhvk/numpy,jakirkham/numpy,endolith/numpy,numpy/numpy,mhvk/numpy,mattip/numpy,seberg/numpy,anntzer/numpy,rgommers/numpy,mattip/numpy,endolith/numpy,jakirkham/numpy,rgommers/numpy,seberg/numpy,numpy/numpy,anntzer/numpy,numpy/numpy,pdebuyl/numpy,pdebuyl/numpy,mhvk/numpy,numpy/numpy,anntzer/numpy,seberg/numpy,rgommers/numpy