Hi Paul,

Here is a proposed patch to make use of the new 'sigsegv' module
(quasi a mini libsigsegv without library dependencies), so that

  * On most systems, catching stack overflow becomes possible without
    link dependencies. (The only notable exceptions, where GNU libsigsegv
    are still needed, are native Windows and older versions of various
    OSes: Mac OS X 10.5, probably NetBSD 7, and such.)

  * In particular, glibc systems are no longer left behind, compared to
    Solaris.

I have verified this patch by building and m4 snapshot with it on
  - glibc
  - newest glibc > 2.33 snapshot
  - Solaris 11/sparc64
  - Cygwin
  - Minix (just to test a case where catching stack overflow is not supported).

And I had tested the 'sigsegv' module on ca. 58 platforms, from IRIX 6.5 to
musl libc on Linux/s390x.

Bruno