Fix _shutting_down not set before finalize._exitfunc
Fix _shutting_down not set before finalize._exitfunc

stuartarchibald/numba,gmarkall/numba,cpcloud/numba,sklam/numba,cpcloud/numba,stuartarchibald/numba,numba/numba,cpcloud/numba,sklam/numba,numba/numba,IntelLabs/numba,numba/numba,gmarkall/numba,stuartarchibald/numba,cpcloud/numba,stonebig/numba,jriehl/numba,stuartarchibald/numba,stonebig/numba,stuartarchibald/numba,stonebig/numba,IntelLabs/numba,seibert/numba,sklam/numba,jriehl/numba,IntelLabs/numba,seibert/numba,stonebig/numba,gmarkall/numba,jriehl/numba,IntelLabs/numba,IntelLabs/numba,jriehl/numba,seibert/numba,gmarkall/numba,gmarkall/numba,sklam/numba,seibert/numba,stonebig/numba,sklam/numba,numba/numba,numba/numba,cpcloud/numba,jriehl/numba,seibert/numba