what does regex depend on sys_wait?

[Sam Steingold]

why am I seeing this?

Module list with included dependencies (indented):
    arg-nonnull
    btowc
    c++defs
    gettext-h
    malloc-gnu
    malloc-posix
  regex
    ssize_t
    stddef
    stdlib
    sys_wait
    unistd
    warn-on-use
    wcrtomb

why are

? modules/regexp/gllib/sys_wait.in.h
? modules/regexp/glm4/sys_wait_h.m4

added to clisp?

thanks.