Fix llvm.memset usage changes in llvm7
Fix llvm.memset usage changes in llvm7

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