Fix the MIBPATH prefix hack

configure.in

@@ -58,7 +58,7 @@ if test -n "$NETSNMP_CONFIG"; then
      NETSNMP_LIBS="`$NETSNMP_CONFIG --libs`"
      NETSNMP_PREFIX="`$NETSNMP_CONFIG --prefix`"
      # Hack to allow distcheck to succeed.
-     if echo "$NETSNMP_PREFIX" | grep -q "^$prefix"; then
+     if test "x$prefix" = "xNONE" || echo "$NETSNMP_PREFIX" | grep -q "^$prefix"; then
          NETSNMP_MIBPATH="$NETSNMP_PREFIX/share/snmp/mibs"
      else
          NETSNMP_MIBPATH="${prefix}${NETSNMP_PREFIX}/share/snmp/mibs"