Spelling fixes in comments, documentation, tests and examples

By klemens <ka7@github.com>

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

networking/udhcp/dhcpc.c

@@ -1460,7 +1460,7 @@ int udhcpc_main(int argc UNUSED_PARAM, char **argv)
 					already_waited_sec += (unsigned)monotonic_sec() - timestamp_before_wait;
 					continue;
 				}
-				/* Else: an error occured, panic! */
+				/* Else: an error occurred, panic! */
 				bb_perror_msg_and_die("select");
 			}
 		}

networking/udhcp/dhcprelay.c

@@ -361,7 +361,7 @@ int dhcprelay_main(int argc, char **argv)
 //   which the reply must be sent (i.e., the host or router interface
 //   connected to the same network as the BOOTP client).  If the content
 //   of the 'giaddr' field does not match one of the relay agent's
-//   directly-connected logical interfaces, the BOOTREPLY messsage MUST be
+//   directly-connected logical interfaces, the BOOTREPLY message MUST be
 //   silently discarded.
 				if (udhcp_read_interface(iface_list[i], NULL, &dhcp_msg.gateway_nip, NULL)) {
 					/* Fall back to our IP on server iface */