[gnome-sudoku] Use AX_REQUIRE_DEFINED in configure.ac

[Michael Catanzaro <mcatanzaro src gnome org>]

commit 469fecc55e2a38e34e1be738c8e8c640f12df175
Author: Michael Catanzaro <mcatanzaro gnome org>
Date:   Sun Nov 6 07:38:46 2016 -0600

    Use AX_REQUIRE_DEFINED in configure.ac
    
    It's good practice anyway, and it seems to avoid this aclocal bug:
    
    aclocal: installing 'm4/ax_require_defined.m4' from
    '/home/mcatanzaro/src/jhbuild/install/share/aclocal/ax_require_defined.m4'
    aclocal: error: too many loops
    aclocal: Please contact <bug-automake gnu org>.
     at /usr/share/automake-1.15/Automake/Channels.pm line 662.
        Automake::Channels::msg("automake", "", "too many loops") called
    at /usr/share/automake-1.15/Automake/ChannelDefs.pm line 212
        Automake::ChannelDefs::prog_error("too many loops") called at
    /usr/bin/aclocal line 1188
    
    which is caused by aclocal discovering after its first run that it needs
    to copy even more macros to our source directory, trying to do so, and
    failing on this assertion.

 configure.ac |    5 +++++
 1 files changed, 5 insertions(+), 0 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index c24ae1b..5a4016c 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1,3 +1,8 @@
+AX_REQUIRE_DEFINED([APPSTREAM_XML])
+AX_REQUIRE_DEFINED([AX_CXX_COMPILE_STDCXX_11])
+AX_REQUIRE_DEFINED([GLIB_GSETTINGS])
+AX_REQUIRE_DEFINED([YELP_HELP_INIT])
+
 AC_PREREQ([2.63])
 AC_INIT([GNOME Sudoku], [3.22.0], [https://bugzilla.gnome.org/],
         [gnome-sudoku], [https://wiki.gnome.org/Apps/Sudoku])