Avoid compiler warning

The field lock_video_orientation may only take values between -1 and 3
(included). But the compiler may trigger a warning on the sprintf()
call, because its type could represent values which could overflow the
string (like "-128"):

> warning: ‘%i’ directive writing between 1 and 4 bytes into a region of
> size 3 [-Wformat-overflow=]

Increase the buffer size to remove the warning.

app/src/server.c

@@ -234,7 +234,7 @@ execute_server(struct server *server, const struct server_params *params) {
     char max_size_string[6];
     char bit_rate_string[11];
     char max_fps_string[6];
-    char lock_video_orientation_string[3];
+    char lock_video_orientation_string[5];
     char display_id_string[6];
     sprintf(max_size_string, "%"PRIu16, params->max_size);
     sprintf(bit_rate_string, "%"PRIu32, params->bit_rate);