Fix two compiler warnings in /sys/lib/dist/cmd.

8c -FTVw -p -I/sys/src/cmd/bzip2/lib unbzip.c
warning: /sys/lib/dist/cmd/bzfs/unbzip.c:[unbzip.c:1655] unreachable code RETURN

8c -FTVw bargraph.c
warning: bargraph.c:43 auto declared and not used: s