MAINT: Remove useless custom tp_alloc and tp_free on ndarray
MAINT: Remove useless custom tp_alloc and tp_free on ndarray

array_alloc is equivalent to the default object allocator
PyType_GenericAlloc. array_free was added "just in case" in e9ebefec but
doesn't seem to serve any actual purpose.

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