Change the version of autoconf which is required to configure from 1.14 to 1.15

From: Maxime Boissonneault <maxime.boissonneault@calculquebec.ca>
Date: Wed, 22 Feb 2017 


diff -ru igraph-0.7.1.orig/aclocal.m4 igraph-0.7.1/aclocal.m4
--- igraph-0.7.1.orig/aclocal.m4	2014-04-22 17:54:54.000000000 +0000
+++ igraph-0.7.1/aclocal.m4	2017-02-21 15:10:50.062279982 +0000
@@ -1,4 +1,4 @@
-# generated automatically by aclocal 1.14 -*- Autoconf -*-
+# generated automatically by aclocal 1.15 -*- Autoconf -*-
 
 # Copyright (C) 1996-2013 Free Software Foundation, Inc.
 
@@ -8619,10 +8619,10 @@
 # generated from the m4 files accompanying Automake X.Y.
 # (This private macro should not be called outside this file.)
 AC_DEFUN([AM_AUTOMAKE_VERSION],
-[am__api_version='1.14'
+[am__api_version='1.15'
 dnl Some users find AM_AUTOMAKE_VERSION and mistake it for a way to
 dnl require some minimum version.  Point them to the right macro.
-m4_if([$1], [1.14], [],
+m4_if([$1], [1.15], [],
       [AC_FATAL([Do not call $0, use AM_INIT_AUTOMAKE([$1]).])])dnl
 ])
 
@@ -8638,7 +8638,7 @@
 # Call AM_AUTOMAKE_VERSION and AM_AUTOMAKE_VERSION so they can be traced.
 # This function is AC_REQUIREd by AM_INIT_AUTOMAKE.
 AC_DEFUN([AM_SET_CURRENT_AUTOMAKE_VERSION],
-[AM_AUTOMAKE_VERSION([1.14])dnl
+[AM_AUTOMAKE_VERSION([1.15])dnl
 m4_ifndef([AC_AUTOCONF_VERSION],
   [m4_copy([m4_PACKAGE_VERSION], [AC_AUTOCONF_VERSION])])dnl
 _AM_AUTOCONF_VERSION(m4_defn([AC_AUTOCONF_VERSION]))])
diff -ru igraph-0.7.1.orig/configure igraph-0.7.1/configure
--- igraph-0.7.1.orig/configure	2014-04-22 17:55:00.000000000 +0000
+++ igraph-0.7.1/configure	2017-02-21 15:10:50.082279777 +0000
@@ -2532,7 +2532,7 @@
 
 
 
-am__api_version='1.14'
+am__api_version='1.15'
 
 ac_aux_dir=
 for ac_dir in "$srcdir" "$srcdir/.." "$srcdir/../.."; do
