Switch cheap pass to use O1.
Switch cheap pass to use O1.

As title, results in similar runtime performance as O2 but at much
cheaper compile time cost.

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