Reproducible build: To avoid build host paths being written into binaries,
accept NETSNMP_CONFIGURE_OPTIONS from the environment.
NETSNMP_CONFIGURE_OPTIONS can be set either null or to a fixed value.

--- net-snmp-5.8.original/configure.ac	2018-11-20 17:41:39.926529072 +1300
+++ net-snmp-5.8/configure.ac	2018-11-20 17:54:44.488180224 +1300
@@ -28,7 +28,7 @@
 #
 # save the configure arguments
 #
-AC_DEFINE_UNQUOTED(NETSNMP_CONFIGURE_OPTIONS,"$ac_configure_args",
+AC_DEFINE_UNQUOTED(NETSNMP_CONFIGURE_OPTIONS,"${NETSNMP_CONFIGURE_OPTIONS-$ac_configure_args}",
   [configure options specified])
 CONFIGURE_OPTIONS="\"$ac_configure_args\""
 AC_SUBST(CONFIGURE_OPTIONS)