gbproxy: Refactor gb_proxy.c into several files

This patch moves several functions and declarations out of gb_proxy.c
to make them reusable by other components and to separate them by
context and task.

Counter enums (prefix is changed to gbproxy_):
  enum gbprox_global_ctr -> gprs/gb_proxy.h
  enum gbprox_peer_ctr -> gprs/gb_proxy.h

Generic Gb parsing (prefix is changed to gprs_gb_):
  struct gbproxy_parse_context -> openbsc/gprs_gb_parse.h
  gbprox_parse_dtap() -> gprs/gprs_gb_parse.c
  gbprox_parse_llc() -> gprs/gprs_gb_parse.c
  gbprox_parse_bssgp() -> gprs/gprs_gb_parse.c
  gbprox_log_parse_context() -> gprs/gprs_gb_parse.c
  *_shift(), *_match() -> gprs/gprs_gb_parse.c (no prefix)
  gbprox_parse_gmm_* -> gprs/gprs_gb_parse.c (static)
  gbprox_parse_gsm_* -> gprs/gprs_gb_parse.c (static)

MI testing/parsing (prefix gprs_ added):
  is_mi_tmsi() -> gprs/gprs_utils.c
  is_mi_imsi() -> gprs/gprs_utils.c
  parse_mi_tmsi() -> gprs/gprs_utils.c

TLLI state handling (prefix is changed to gbproxy_):
  gbprox_*tlli* -> gprs/gb_proxy_tlli.c
  (except gbprox_patch_tlli, gbproxy_make_sgsn_tlli)

Message patching (prefix is changed to gbproxy_):
  gbprox_*patch* -> gprs/gb_proxy_patch.c
  gbprox_check_imsi -> gprs/gb_proxy_patch.c

Sponsored-by: On-Waves ehf
diff --git a/openbsc/src/gprs/gb_proxy_vty.c b/openbsc/src/gprs/gb_proxy_vty.c
index a85f439..b2f25a3 100644
--- a/openbsc/src/gprs/gb_proxy_vty.c
+++ b/openbsc/src/gprs/gb_proxy_vty.c
@@ -198,7 +198,7 @@
 		talloc_free(g_cfg->core_apn);
 		g_cfg->core_apn = NULL;
 		g_cfg->core_apn_size = 0;
-		gbprox_clear_patch_filter(g_cfg);
+		gbproxy_clear_patch_filter(g_cfg);
 		return CMD_SUCCESS;
 	}
 
@@ -211,8 +211,8 @@
 	}
 
 	if (!filter) {
-		gbprox_clear_patch_filter(g_cfg);
-	} else if (gbprox_set_patch_filter(g_cfg, filter, &err_msg) != 0) {
+		gbproxy_clear_patch_filter(g_cfg);
+	} else if (gbproxy_set_patch_filter(g_cfg, filter, &err_msg) != 0) {
 		vty_out(vty, "Match expression invalid: %s%s",
 			err_msg, VTY_NEWLINE);
 		return CMD_WARNING;
@@ -551,7 +551,7 @@
 	state = &peer->patch_state;
 
 	if (match == MATCH_STALE) {
-		found = gbprox_remove_stale_tllis(peer, time(NULL));
+		found = gbproxy_remove_stale_tllis(peer, time(NULL));
 		if (found)
 			vty_out(vty, "Deleted %d stale TLLI%s%s",
 				found, found == 1 ? "" : "s", VTY_NEWLINE);
@@ -573,7 +573,7 @@
 		}
 		vty_out(vty, "Deleting TLLI %08x%s", tlli_info->tlli.current,
 			VTY_NEWLINE);
-		gbprox_delete_tlli(peer, tlli_info);
+		gbproxy_delete_tlli(peer, tlli_info);
 		found += 1;
 	}