res_rtp_asterisk.c: Don't truncate spec-compliant `ice-ufrag` or `ice-pwd`.

RFC 8839[1] indicates that the `ice-ufrag` and `ice-pwd` attributes
can be up to 256 bytes long. While we don't generate values of that
size, we should be able to accomodate them without truncating.

1. https://www.rfc-editor.org/rfc/rfc8839#name-ice-ufrag-and-ice-pwd-attri

(cherry picked from commit 3cafe10d21)

res/res_rtp_asterisk.c

@@ -495,11 +495,11 @@ struct ast_rtp {
 
 	struct ast_rtp_ioqueue_thread *ioqueue; /*!< The ioqueue thread handling us */
 
-	char remote_ufrag[256];  /*!< The remote ICE username */
-	char remote_passwd[256]; /*!< The remote ICE password */
+	char remote_ufrag[257];  /*!< The remote ICE username */
+	char remote_passwd[257]; /*!< The remote ICE password */
 
-	char local_ufrag[256];  /*!< The local ICE username */
-	char local_passwd[256]; /*!< The local ICE password */
+	char local_ufrag[257];  /*!< The local ICE username */
+	char local_passwd[257]; /*!< The local ICE password */
 
 	struct ao2_container *ice_local_candidates;           /*!< The local ICE candidates */
 	struct ao2_container *ice_active_remote_candidates;   /*!< The remote ICE candidates */