getopt isn't used anymore, and getent itself is optional.

getopt doesn't work very well in the BSDs, and getent has plenty of
fallbacks to replace it when it's not available.

<https://github.com/terrycloth/fish-shell/commit/
47a768ceeaef1d702624802d83338edbcc0f377c#commitcomment-23613921>

README.md

@@ -31,8 +31,6 @@ At runtime, fish requires:
     * an awk implementation, such as gawk, mawk, etc
     * coreutils --- at least basename, cat, cut, date, dircolors, dirname, ls, mkdir, mkfifo, mktemp, rm, seq, sort, stat, stty, tail, tr, tty, uname, uniq, wc, whoami
     * find
-    * getent (part of glibc)
-    * getopt
     * grep
     * hostname
     * kill