ast_format_cap: Avoid format creation on module load, use cache instead.

Since Asterisk 13, formats are immutable and cached. However while loading a
module like chan_sip, some formats were created instead using cached ones.

ASTERISK-25535 #close

Change-Id: I479cdc220d5617c840a98f3389b3bd91e91fbd9b

main/format_cap.c

@@ -230,7 +230,10 @@ int ast_format_cap_append_by_type(struct ast_format_cap *cap, enum ast_media_typ
 			continue;
 		}
 
-		format = ast_format_create(codec);
+		format = ast_format_cache_get(codec->name);
+		if (!format || (codec != ast_format_get_codec(format))) {
+			format = ast_format_create(codec);
+		}
 		ao2_ref(codec, -1);
 
 		if (!format) {