build: add macro dirs to configure_ac

Per suggestion from autotools during configuration, add macro dirs

Change-Id: I95c96eb9e7339cc8f5cd1c19fdcdad79b48b4e1a
Signed-off-by: Patrick Venture <venture@google.com>
diff --git a/configure.ac b/configure.ac
index 2abafda..47058ec 100644
--- a/configure.ac
+++ b/configure.ac
@@ -2,6 +2,8 @@
 AC_PREREQ([2.69])
 AC_INIT([pam_ipmi], [0.1], [https://github.com/openbmc/pam-ipmi/issues])
 AC_CONFIG_HEADERS([config.h])
+AC_CONFIG_MACRO_DIRS([m4])
+AC_CONFIG_AUX_DIR([build-aux])
 AM_INIT_AUTOMAKE([subdir-objects -Wall foreign dist-xz])
 AM_SILENT_RULES([yes])