MAINT: Push down declarations in _convert_from_dict
MAINT: Push down declarations in _convert_from_dict

This makes it easier to reason about which variables contain mutable state.
C99 makes some of this possible, while other parts were already possible.

grlee77/numpy,grlee77/numpy,mattip/numpy,seberg/numpy,grlee77/numpy,jakirkham/numpy,mattip/numpy,charris/numpy,mhvk/numpy,madphysicist/numpy,jakirkham/numpy,pdebuyl/numpy,anntzer/numpy,mattip/numpy,charris/numpy,mhvk/numpy,jakirkham/numpy,seberg/numpy,madphysicist/numpy,grlee77/numpy,rgommers/numpy,endolith/numpy,jakirkham/numpy,pbrod/numpy,jakirkham/numpy,madphysicist/numpy,abalkin/numpy,WarrenWeckesser/numpy,pdebuyl/numpy,numpy/numpy,seberg/numpy,grlee77/numpy,mhvk/numpy,charris/numpy,anntzer/numpy,simongibbons/numpy,charris/numpy,rgommers/numpy,numpy/numpy,mhvk/numpy,pbrod/numpy,pbrod/numpy,anntzer/numpy,abalkin/numpy,simongibbons/numpy,simongibbons/numpy,simongibbons/numpy,rgommers/numpy,mhvk/numpy,endolith/numpy,numpy/numpy,endolith/numpy,WarrenWeckesser/numpy,rgommers/numpy,madphysicist/numpy,seberg/numpy,pbrod/numpy,simongibbons/numpy,WarrenWeckesser/numpy,WarrenWeckesser/numpy,pbrod/numpy,numpy/numpy,endolith/numpy,madphysicist/numpy,mattip/numpy,anntzer/numpy,abalkin/numpy,pdebuyl/numpy,pdebuyl/numpy,WarrenWeckesser/numpy