include_next: silence autoconf 2.68 warning
Next warning spotted by Autoconf; this time it is spurious (when
checking for a working include_next, we could care less what other
defines have already been provided by AC_DEFINE). Which makes this
the first real-world use case outside of autoconf guts that can
reasonably use the new autoconf macro.
* m4/include_next.m4 (gl_INCLUDE_NEXT): Mark this use of
AC_COMPILE_IFELSE as special.
(AC_LANG_DEFINES_PROVIDED): Provide dummy implementation for
autoconf < 2.68.
Signed-off-by: Eric Blake <eblake@redhat.com>
projects / pspp / commit