gtphub: cosmetic: rename a file.

gtphub_ext.c's initial purpose was to wrap a specific function. The file
then turned into everything related to DNS, which fits pretty well. Rename
to gtphub_ares.c.

Tweak the header comment to reflect the new file name.

Sponsored-by: On-Waves ehi

openbsc/include/openbsc/gtphub.h

@@ -408,7 +408,7 @@ struct gtphub {
 	struct nr_map tei_map[GTPH_PLANE_N];
 	struct nr_pool tei_pool[GTPH_PLANE_N];
 
-	struct llist_head ggsn_lookups; /* opaque (gtphub_ext.c) */
+	struct llist_head ggsn_lookups; /* opaque (gtphub_ares.c) */
 	struct llist_head resolved_ggsns; /* struct gtphub_resolved_ggsn */
 
 	struct osmo_timer_list gc_timer;

openbsc/src/gprs/Makefile.am

@@ -34,7 +34,7 @@ osmo_sgsn_LDADD = 	\
 			-lgtp $(OSMO_LIBS) $(LIBOSMOABIS_LIBS) $(LIBCARES_LIBS) \
 			$(LIBCRYPTO_LIBS) -lrt
 
-osmo_gtphub_SOURCES =	gtphub_main.c gtphub.c gtphub_ext.c gtphub_vty.c \
+osmo_gtphub_SOURCES =	gtphub_main.c gtphub.c gtphub_ares.c gtphub_vty.c \
 			sgsn_ares.c gprs_utils.c
 osmo_gtphub_LDADD = 	\
 			$(top_builddir)/src/libcommon/libcommon.a \

openbsc/src/gprs/gtphub_ares.c

@@ -3,9 +3,11 @@
 /* (C) 2015 by sysmocom s.f.m.c. GmbH <info@sysmocom.de>
  * All Rights Reserved
  *
- * gtphub_ext.c -- ext means extern. This file is kept separate so that these
- * functions can be wrapped for gtphub_test.c. When a function and its callers
- * are in the same compilational unit, the wrappability may be optimized away.
+ * gtphub_ares.c.
+ *
+ * This file is kept separate so that these functions can be wrapped for
+ * gtphub_test.c. When a function and its callers are in the same compilational
+ * unit, the wrappability may be optimized away.
  *
  * Author: Neels Hofmeyr
  *