build failure on Solaris 11.4

Hi,

On Solaris 11.4/x86_64, the newest release m4-1.4.18 exhibits a "make check"
failure of 'test-localename':

FAIL: test-localename
=====================

../../tests/test-localename.c:183: assertion 'strcmp (name, "fr_FR.UTF-8") == 0' failed
../../build-aux/test-driver: line 107: 14852: Abort(coredump)
FAIL test-localename (exit status: 262)


This is fixed in the current m4 snapshot that can be downloaded from
https://gitlab.com/gnu-m4/ci-distcheck/

Bruno