Port recent ngettext stub to non-glibc

* src/editfns.c: Don’t try to call glibc ngettext;
we’re not ready for that yet.
(Fngettext): Do not restrict integer arguments to fixnums.
Improve doc string a bit.
1 job for master in 60 minutes and 2 seconds (queued for 3 seconds)
Status Job ID Name Coverage
  Test
failed #1132
test-all

01:00:02

 
Name Stage Failure
failed
test-all Test The script exceeded the maximum execution time set for the job
  GEN      lisp/international/ccl-tests.log
ELC lisp/international/mule-tests.elc
GEN lisp/international/mule-tests.log
ELC lisp/international/mule-util-tests.elc
GEN lisp/international/mule-util-tests.log
ELC lisp/international/ucs-normalize-tests.elc
GEN lisp/international/ucs-normalize-tests.log
Pulling docker image gitlab/gitlab-runner-helper:x86_64-f100a208 ...
ERROR: Job failed: execution took longer than 1h0m0s seconds