switch to libosmocore multihread-logging

When osmo-remsim was originally developed, libosmocore logging was
not yet thread-safe.  This meant that the worker threads of remsim-bankd
and remsim-server could not log via the libosmocore logging framework
but directly used stderr/stdout, which produced rather inconsistent log
output.

However, since 1.3.0, libosmocore has received support for
multi-threaded applications.  Let's make use of this and consistently
use it in remsim-server and remsim-bankd.  This obviously also means
adding some more log categories.

Change-Id: I7bd5264c559b756927046563a2d00c54826bee9b
diff --git a/src/slotmap.c b/src/slotmap.c
index b837f01..fe0c6b7 100644
--- a/src/slotmap.c
+++ b/src/slotmap.c
@@ -103,14 +103,14 @@
 
 	map = slotmap_by_bank(maps, bank);
 	if (map) {
-		fprintf(stderr, "BANKD %u:%u already in use, cannot add new map\n",
+		LOGP(DSLOTMAP, LOGL_ERROR, "BANKD %u:%u already in use, cannot add new map\n",
 			bank->bank_id, bank->slot_nr);
 		return NULL;
 	}
 
 	map = slotmap_by_client(maps, client);
 	if (map) {
-		fprintf(stderr, "CLIENT %u:%u already in use, cannot add new map\n",
+		LOGP(DSLOTMAP, LOGL_ERROR, "CLIENT %u:%u already in use, cannot add new map\n",
 			client->client_id, client->slot_nr);
 		return NULL;
 	}
@@ -132,7 +132,7 @@
 #endif
 	slotmaps_unlock(maps);
 
-	printf("Slot Map %s added\n", slotmap_name(mapname, sizeof(mapname), map));
+	LOGP(DSLOTMAP, LOGL_INFO, "Slot Map %s added\n", slotmap_name(mapname, sizeof(mapname), map));
 
 	return map;
 }
@@ -142,7 +142,7 @@
 {
 	char mapname[64];
 
-	printf("Slot Map %s deleted\n", slotmap_name(mapname, sizeof(mapname), map));
+	LOGP(DSLOTMAP, LOGL_INFO, "Slot Map %s deleted\n", slotmap_name(mapname, sizeof(mapname), map));
 
 	llist_del(&map->list);
 #ifdef REMSIM_SERVER