gbproxy: Use a separate regexp for routing

Currently one regexp ('patching') is used for all matching.

This patch adds a second category 'routing' which is exclusively used
for SGSN selection. It also adds a corresponding VTY command:

  - match-imsi patching RE : MS related patching (currently APN)
  - match-imsi routing RE  : Select secondary SGSN on match only
  - no match-imsi          : Clear all filter expressions

Ticket: OW#1258
Sponsored-by: On-Waves ehf
diff --git a/openbsc/tests/gbproxy/gbproxy_test.c b/openbsc/tests/gbproxy/gbproxy_test.c
index 5b298de..5aa301b 100644
--- a/openbsc/tests/gbproxy/gbproxy_test.c
+++ b/openbsc/tests/gbproxy/gbproxy_test.c
@@ -2786,7 +2786,7 @@
 	gbcfg.route_to_sgsn2 = 1;
 	gbcfg.nsip_sgsn2_nsei = SGSN2_NSEI;
 
-	if (gbproxy_set_patch_filter(&gbcfg.matches[GBPROX_MATCH_PATCHING],
+	if (gbproxy_set_patch_filter(&gbcfg.matches[GBPROX_MATCH_ROUTING],
 				     filter_re, &err_msg) != 0) {
 		fprintf(stderr, "gbprox_set_patch_filter: got error: %s\n",
 			err_msg);
@@ -3219,7 +3219,7 @@
 
 	dump_global(stdout, 0);
 
-	gbproxy_clear_patch_filter(&gbcfg.matches[GBPROX_MATCH_PATCHING]);
+	gbproxy_clear_patch_filter(&gbcfg.matches[GBPROX_MATCH_ROUTING]);
 	gbprox_reset(&gbcfg);
 	gprs_ns_destroy(nsi);
 	nsi = NULL;