Add test_constant_functions.
Add test_constant_functions.

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