m4 1.4.18b testing results

[Bruno Haible]

I tested m4-1.4.18b and subsequent tarballs (with fixes included)
on some platforms. Aside from
  - the problems reported here and in bug-gnulib,
  - a couple of gnulib unit tests that fail on some of the less
    important platforms,

the build went fine and all unit tests passed on:

Linux x86_64: Ubuntu 16.04, CentOS 5,6,7,8, Fedora 13,33, openSUSE 15.2
Linux x86_64 with musl libc: Alpine Linux 3.13
Linux x64_64-x32
Linux i386: Ubuntu 16.04
Linux/arm64
Linux/arm64 with musl libc
Linux/arm
Linux/powerpc64le
Linux/powerpc64le with musl libc
Linux/powerpc 64-bit,32-bit
Linux/s390x 64-bit,32-bit
Linux/s390x with musl libc
Linux/sparc 64-bit,32-bit
Linux/mips 32,n32,64
Linux/ia64
Linux/hppa
Linux/riscv64
Linux/alpha
FreeBSD 12/x86_64
FreeBSD 12/i386
FreeBSD 13/arm64
NetBSD 8 64-bit,32-bit
OpenBSD 6.9/x86_64
Hurd 2019
macOS 11/arm64
Solaris 10/x86_64 64-bit,32-bit
Solaris 10/sparc 64-bit,32-bit
Solaris 11.4/x86_64 64-bit,32-bit
Solaris 11.3/sparc 32-bit
Solaris 11 OmniOS 64-bit,32-bit
Solaris 11 OpenIndiana 64-bit,32-bit
AIX 7.1 64-bit,32-bit
IRIX 6.5
Minix 3.3
Cygwin 2.9

In other words: Things look good. :-)

Bruno