new AC_USE_SYSTEM_EXTENSIONS breaks Interix?

[Jerker Bäck]

What's wrong?

reconf bison 2.3  - x86_64 Interix 6.0 with GNU m4-1.4.8 
$ uname -a
Interix max 6.0 10.0.6000.0 EM64T Intel_EM64T_Family_15_Model_6_Stepping_5
$ autoreconf -vfi
autoreconf: Entering directory `.'
autoreconf: running: autopoint --force
autoreconf: running: aclocal --force -I m4
configure.ac:45: warning: AC_COMPILE_IFELSE was called before 
AC_USE_SYSTEM_EXTENSIONS
../../../lib/autoconf/specific.m4:383: AC_USE_SYSTEM_EXTENSIONS is expanded 
from...
../../../lib/autoconf/specific.m4:449: AC_AIX is expanded from...
m4/extensions.m4:15: gl_USE_SYSTEM_EXTENSIONS is expanded from...
configure.ac:45: the top level
configure.ac:45: warning: AC_RUN_IFELSE was called before 
AC_USE_SYSTEM_EXTENSIONS
../../../lib/autoconf/specific.m4:454: AC_MINIX is expanded from...
autoreconf: configure.ac: tracing
configure.ac:45: warning: AC_COMPILE_IFELSE was called before 
AC_USE_SYSTEM_EXTENSIONS
../../../lib/autoconf/specific.m4:383: AC_USE_SYSTEM_EXTENSIONS is expanded 
from...
../../../lib/autoconf/specific.m4:449: AC_AIX is expanded from...
m4/extensions.m4:15: gl_USE_SYSTEM_EXTENSIONS is expanded from...
configure.ac:45: the top level
configure.ac:45: warning: AC_RUN_IFELSE was called before 
AC_USE_SYSTEM_EXTENSIONS
../../../lib/autoconf/specific.m4:454: AC_MINIX is expanded from...
autoreconf: configure.ac: not using Libtool
autoreconf: running: /usr/local/bin/autoconf --force
configure.ac:45: warning: AC_COMPILE_IFELSE was called before 
AC_USE_SYSTEM_EXTENSIONS
../../../lib/autoconf/specific.m4:383: AC_USE_SYSTEM_EXTENSIONS is expanded 
from...
../../../lib/autoconf/specific.m4:449: AC_AIX is expanded from...
m4/extensions.m4:15: gl_USE_SYSTEM_EXTENSIONS is expanded from...
configure.ac:45: the top level
configure.ac:45: warning: AC_RUN_IFELSE was called before 
AC_USE_SYSTEM_EXTENSIONS
../../../lib/autoconf/specific.m4:454: AC_MINIX is expanded from...
autoreconf: running: /usr/local/bin/autoheader --force
configure.ac:45: warning: AC_COMPILE_IFELSE was called before 
AC_USE_SYSTEM_EXTENSIONS
../../../lib/autoconf/specific.m4:383: AC_USE_SYSTEM_EXTENSIONS is expanded 
from...
../../../lib/autoconf/specific.m4:449: AC_AIX is expanded from...
m4/extensions.m4:15: gl_USE_SYSTEM_EXTENSIONS is expanded from...
configure.ac:45: the top level
configure.ac:45: warning: AC_RUN_IFELSE was called before 
AC_USE_SYSTEM_EXTENSIONS
../../../lib/autoconf/specific.m4:454: AC_MINIX is expanded from...
autoheader: warning: missing template: _ALL_SOURCE
autoheader: Use AC_DEFINE([_ALL_SOURCE], [], [Description])
autoheader: warning: missing template: _GNU_SOURCE
autoheader: warning: missing template: _TANDEM_SOURCE
autoreconf: failed to run /usr/local/bin/autoheader: Invalid seek on 
non-seekable object

Thanks, Jerker Bäck