configure.ac: remove unneeded AC_CONFIG_MACRO_DIR([m4])

Makefile.am already contains "ACLOCAL_AMFLAGS = -I m4",
that is enough for autoreconf to do the right thing.

Tested with
autoreconf -if && ./configure --enable-maintainer-mode && make && make distcheck

Signed-off-by: Dmitry V. Levin <ldv@altlinux.org>
diff --git a/ChangeLog b/ChangeLog
index 2b2f743..28a11e7 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+2020-12-15  Dmitry V. Levin  <ldv@altlinux.org>
+
+	* configure.ac (AC_CONFIG_MACRO_DIR): Remove.
+
 2020-12-12  Dmitry V. Levin  <ldv@altlinux.org>
 
 	* configure.ac: Fix spelling typos in comments.
diff --git a/configure.ac b/configure.ac
index 9e29f16..268a467 100644
--- a/configure.ac
+++ b/configure.ac
@@ -57,7 +57,6 @@
 AC_CONFIG_FILES([Makefile])
 AC_CONFIG_HEADERS([config.h])
 
-AC_CONFIG_MACRO_DIR([m4])
 AC_CONFIG_FILES([m4/Makefile])
 
 dnl The RPM spec file.  We substitute a few values in the file.