build-gnu.sh: Let md5sum.pl clap compatible #4731

Job	Run time
Run benchmarks (CodSpeed) (uu_cut)	2m 49s
Run benchmarks (CodSpeed) (uu_du)	3m 27s
Run benchmarks (CodSpeed) (uu_dd)	3m 20s
Run benchmarks (CodSpeed) (uu_base64)	9m 2s
Run benchmarks (CodSpeed) (uu_cksum)	9m 17s
Run benchmarks (CodSpeed) (uu_cp)	2m 5s
Run benchmarks (CodSpeed) (uu_expand)	1m 40s
Run benchmarks (CodSpeed) (uu_fold)	1m 15s
Run benchmarks (CodSpeed) (uu_mv)	2m 6s
Run benchmarks (CodSpeed) (uu_rm)	1m 35s
Run benchmarks (CodSpeed) (uu_shuf)	1m 25s
Run benchmarks (CodSpeed) (uu_nl)	2m 9s
Run benchmarks (CodSpeed) (uu_ls)	2m 48s
Run benchmarks (CodSpeed) (uu_join)	2m 15s
Run benchmarks (CodSpeed) (uu_unexpand)	2m 39s
Run benchmarks (CodSpeed) (uu_date)	1m 38s
Run benchmarks (CodSpeed) (uu_tsort)	3m 1s
Run benchmarks (CodSpeed) (uu_split)	2m 32s
Run benchmarks (CodSpeed) (uu_sort)	6m 27s
Run benchmarks (CodSpeed) (uu_numfmt)	2m 33s
Run benchmarks (CodSpeed) (uu_uniq)	1m 38s
Run benchmarks (CodSpeed) (uu_wc)	12m 58s
Run benchmarks (CodSpeed) (uu_seq)	1m 19s
Run benchmarks (CodSpeed) (uu_factor)	1m 42s
	1h 21m 40s

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