diff --git a/aclocal/ax_check_openssl.m4 b/aclocal/ax_check_openssl.m4
index a87c5a6..28e48cb 100644
--- a/aclocal/ax_check_openssl.m4
+++ b/aclocal/ax_check_openssl.m4
@@ -1,5 +1,5 @@
 # ===========================================================================
-#     http://www.gnu.org/software/autoconf-archive/ax_check_openssl.html
+#     https://www.gnu.org/software/autoconf-archive/ax_check_openssl.html
 # ===========================================================================
 #
 # SYNOPSIS
@@ -32,7 +32,7 @@
 #   and this notice are preserved. This file is offered as-is, without any
 #   warranty.
 
-#serial 8
+#serial 10
 
 AU_ALIAS([CHECK_SSL], [AX_CHECK_OPENSSL])
 AC_DEFUN([AX_CHECK_OPENSSL], [
@@ -51,7 +51,7 @@
         ], [
             # if pkg-config is installed and openssl has installed a .pc file,
             # then use that information and don't search ssldirs
-            AC_PATH_PROG([PKG_CONFIG], [pkg-config])
+            AC_CHECK_TOOL([PKG_CONFIG], [pkg-config])
             if test x"$PKG_CONFIG" != x""; then
                 OPENSSL_LDFLAGS=`$PKG_CONFIG openssl --libs-only-L 2>/dev/null`
                 if test $? = 0; then
diff --git a/aclocal/m4_ax_compare_version.m4 b/aclocal/ax_compare_version.m4
similarity index 98%
rename from aclocal/m4_ax_compare_version.m4
rename to aclocal/ax_compare_version.m4
index 74dc0fd..9c8e208 100644
--- a/aclocal/m4_ax_compare_version.m4
+++ b/aclocal/ax_compare_version.m4
@@ -1,5 +1,5 @@
 # ===========================================================================
-#    http://www.gnu.org/software/autoconf-archive/ax_compare_version.html
+#    https://www.gnu.org/software/autoconf-archive/ax_compare_version.html
 # ===========================================================================
 #
 # SYNOPSIS
@@ -79,7 +79,7 @@
 #   and this notice are preserved. This file is offered as-is, without any
 #   warranty.
 
-#serial 11
+#serial 12
 
 dnl #########################################################################
 AC_DEFUN([AX_COMPARE_VERSION], [
diff --git a/aclocal/ax_lua.m4 b/aclocal/ax_lua.m4
index 9feb352..5920167 100644
--- a/aclocal/ax_lua.m4
+++ b/aclocal/ax_lua.m4
@@ -1,5 +1,5 @@
 # ===========================================================================
-#          http://www.gnu.org/software/autoconf-archive/ax_lua.html
+#          https://www.gnu.org/software/autoconf-archive/ax_lua.html
 # ===========================================================================
 #
 # SYNOPSIS
@@ -166,7 +166,7 @@
 #   Public License for more details.
 #
 #   You should have received a copy of the GNU General Public License along
-#   with this program. If not, see <http://www.gnu.org/licenses/>.
+#   with this program. If not, see <https://www.gnu.org/licenses/>.
 #
 #   As a special exception, the respective Autoconf Macro's copyright owner
 #   gives unlimited permission to copy, distribute and modify the configure
@@ -181,7 +181,7 @@
 #   modified version of the Autoconf Macro, you may extend this special
 #   exception to the GPL to apply to your modified version as well.
 
-#serial 39
+#serial 40
 
 dnl =========================================================================
 dnl AX_PROG_LUA([MINIMUM-VERSION], [TOO-BIG-VERSION],
diff --git a/aclocal/ax_prog_dotnetcore_version.m4 b/aclocal/ax_prog_dotnetcore_version.m4
index 45c7a4e..92c7495 100644
--- a/aclocal/ax_prog_dotnetcore_version.m4
+++ b/aclocal/ax_prog_dotnetcore_version.m4
@@ -1,6 +1,6 @@
-# ==============================================================================
-#  http://www.gnu.org/software/autoconf-archive/ax_prog_dotnetcore_version.html
-# ==============================================================================
+# ===============================================================================
+#  https://www.gnu.org/software/autoconf-archive/ax_prog_dotnetcore_version.html
+# ===============================================================================
 #
 # SYNOPSIS
 #
@@ -33,7 +33,7 @@
 #   and this notice are preserved. This file is offered as-is, without any
 #   warranty.
 
-#serial 1
+#serial 2
 
 AC_DEFUN([AX_PROG_DOTNETCORE_VERSION],[
     AC_REQUIRE([AC_PROG_SED])
diff --git a/aclocal/ax_prog_haxe_version.m4 b/aclocal/ax_prog_haxe_version.m4
index 3dee430..fcacc67 100644
--- a/aclocal/ax_prog_haxe_version.m4
+++ b/aclocal/ax_prog_haxe_version.m4
@@ -1,5 +1,5 @@
 # ===========================================================================
-#   http://www.gnu.org/software/autoconf-archive/ax_prog_haxe_version.html
+#   https://www.gnu.org/software/autoconf-archive/ax_prog_haxe_version.html
 # ===========================================================================
 #
 # SYNOPSIS
@@ -32,7 +32,7 @@
 #   and this notice are preserved. This file is offered as-is, without any
 #   warranty.
 
-#serial 1
+#serial 2
 
 AC_DEFUN([AX_PROG_HAXE_VERSION],[
     AC_REQUIRE([AC_PROG_SED])
diff --git a/aclocal/ax_prog_perl_modules.m4 b/aclocal/ax_prog_perl_modules.m4
index 11a326c..70b3230 100644
--- a/aclocal/ax_prog_perl_modules.m4
+++ b/aclocal/ax_prog_perl_modules.m4
@@ -1,5 +1,5 @@
 # ===========================================================================
-#   http://www.gnu.org/software/autoconf-archive/ax_prog_perl_modules.html
+#   https://www.gnu.org/software/autoconf-archive/ax_prog_perl_modules.html
 # ===========================================================================
 #
 # SYNOPSIS
@@ -32,7 +32,7 @@
 #   and this notice are preserved. This file is offered as-is, without any
 #   warranty.
 
-#serial 7
+#serial 8
 
 AU_ALIAS([AC_PROG_PERL_MODULES], [AX_PROG_PERL_MODULES])
 AC_DEFUN([AX_PROG_PERL_MODULES],[dnl