While building llpp with ocaml 5.0 hit a snag - the compiler warned me
that unix (and str) are no longer in the default path and suggested to
add +unix|+str, which, i did only to find that ocamldep does something
build.bash wasn't prepared to handle:

- ~/xsrc/sbor/llpp/build/bin/ocamldep -bytecode -I +unix main.ml 
main.cmo : \
    utils.cmi \
    utf8syms.cmo \
    /home/malc/xsrc/sbor/llpp/build/lib/ocaml/unix/unix.cmi \
    uiutils.cmi \
    keys.cmi \
    help.cmi \
    glutils.cmi \
    ffi.cmo \
    config.cmo \
    main.cmi

Namely the (absolute) unix.cmi dependency. After minor build.bash
massage build process completed successfully, mentioning it since that
the change of behavior seemed arbitrary and potentially unintended.