I'm trying to port libisofs to Windows. My environment is MSYS2 with mingw-w64-i686 toolchain installed.
I've used gnulib for missing headers with
gnulib-tool --import command:
$ ../gnulib/gnulib-tool --import fnmatch
I've done all steps in instruction:
Don't forget to
  - add "lib/Makefile" to AC_CONFIG_FILES in ./configure.ac,
  - mention "lib" in SUBDIRS in Makefile.am,
  - mention "-I m4" in ACLOCAL_AMFLAGS in Makefile.am,
  - mention "m4/gnulib-cache.m4" in EXTRA_DIST in Makefile.am,
  - invoke gl_EARLY in ./configure.ac, right after AC_PROG_CC,
  - invoke gl_INIT in ./configure.ac.
Altough, there was no AC_PROG_CC in configure.ac, so I've added gl_EARLY after AM_PROG_CC_C_O
And there was no SUBDIRS variable in Makefile.am so I've added it manually at the bottom, as so:
SUBDIRS = lib
All configurations I've made as so:
autoreconf -i
automake --add-missing
autoconf
./configure
After running make I recieve error:
hard-locale.c:19:10: fatal error: config.h: No such file or directory
 #include <config.h>
As I understand that file must be created by ./configure, but I don't understand why compiler doesn't find it.
configure.ac: https://pastebin.com/JbWRqjEv 
Makefile.am: https://pastebin.com/V6ZBq8Vd 
All outputs: https://pastebin.com/WFu5aJU7