[tomboy] build: add ax_require_config macro copy to our code

[Alex Tereschenko <alexter src gnome org>]

commit 28c868b7095fc19f032a376226a676f2c5889114
Author: Alex Tereschenko <frozen and blue gmail com>
Date:   Sun Nov 20 15:38:36 2016 +0100

    build: add ax_require_config macro copy to our code
    
    This is to alleviate the problem with building the package on distros
    with older autoconf-archive version, which does not include this macro.
    Ubuntu 14 is one such distro.
    
    aclocal will overwrite our version if the OS has a newer version,
    as determined by the "serial" line in the macro.
    
    We will not track other files in m4 directory though,
    as the assumption is that such cases should be rare.
    
    Closes #26.
    
    Signed-off-by: Alex Tereschenko <frozen and blue gmail com>

 .gitignore               |    1 -
 m4/.gitignore            |    3 +++
 m4/ax_require_defined.m4 |   37 +++++++++++++++++++++++++++++++++++++
 3 files changed, 40 insertions(+), 1 deletions(-)
---
diff --git a/.gitignore b/.gitignore
index 78077a8..f7ea246 100644
--- a/.gitignore
+++ b/.gitignore
@@ -12,7 +12,6 @@ Makefile.in
 /*.userprefs
 /*.usertasks
 /.vs
-/m4
 /configure
 /config.*
 /config.status
diff --git a/m4/.gitignore b/m4/.gitignore
new file mode 100644
index 0000000..d1f1df1
--- /dev/null
+++ b/m4/.gitignore
@@ -0,0 +1,3 @@
+*
+!.gitignore
+!ax_require_defined.m4
diff --git a/m4/ax_require_defined.m4 b/m4/ax_require_defined.m4
new file mode 100644
index 0000000..cae1111
--- /dev/null
+++ b/m4/ax_require_defined.m4
@@ -0,0 +1,37 @@
+# ===========================================================================
+#    http://www.gnu.org/software/autoconf-archive/ax_require_defined.html
+# ===========================================================================
+#
+# SYNOPSIS
+#
+#   AX_REQUIRE_DEFINED(MACRO)
+#
+# DESCRIPTION
+#
+#   AX_REQUIRE_DEFINED is a simple helper for making sure other macros have
+#   been defined and thus are available for use.  This avoids random issues
+#   where a macro isn't expanded.  Instead the configure script emits a
+#   non-fatal:
+#
+#     ./configure: line 1673: AX_CFLAGS_WARN_ALL: command not found
+#
+#   It's like AC_REQUIRE except it doesn't expand the required macro.
+#
+#   Here's an example:
+#
+#     AX_REQUIRE_DEFINED([AX_CHECK_LINK_FLAG])
+#
+# LICENSE
+#
+#   Copyright (c) 2014 Mike Frysinger <vapier gentoo org>
+#
+#   Copying and distribution of this file, with or without modification, are
+#   permitted in any medium without royalty provided the copyright notice
+#   and this notice are preserved. This file is offered as-is, without any
+#   warranty.
+
+#serial 1
+
+AC_DEFUN([AX_REQUIRE_DEFINED], [dnl
+  m4_ifndef([$1], [m4_fatal([macro ]$1[ is not defined; is a m4 file missing?])])
+])dnl AX_REQUIRE_DEFINED