GNU M4 1.4.15 uses a buggy replacement strstr...

Hi Everyone,

I'm trying to update Bison on Solaris 11.3. Configure is failing with:

checking for GNU M4 that supports accurate traces... configure: error:
no acceptable m4 could be found in $PATH.
GNU M4 1.4.6 or later is required; 1.4.16 or newer is recommended.
GNU M4 1.4.15 uses a buggy replacement strstr on some systems.
Glibc 2.9 - 2.12 and GNU M4 1.4.11 - 1.4.15 have another strstr bug.

Gnulib has strstr. Perhaps you can use it instead of spending time
with the old or buggy versions. Also see
https://www.gnu.org/software/gnulib/manual/gnulib.html#c_002dstrstr.

Jeff