Lock/unlock config to avoid infinite recursion (#1031)

Closes: #996

src/btop_input.cpp

@@ -288,6 +288,8 @@ namespace Input {
 						Config::set("proc_filtering", false);
 						old_filter.clear();
 						if(key == "down"){
+							Config::unlock();
+							Config::lock();
 							process("down");
 							return;
 						}