Misc: Make struct member functions file-local

src/util/input_manager.cpp

@@ -27,6 +27,8 @@
 
 Log_SetChannel(InputManager);
 
+namespace {
+
 // ------------------------------------------------------------------------
 // Constants
 // ------------------------------------------------------------------------
@@ -88,6 +90,8 @@ struct MacroButton
   bool trigger_state;       ///< Whether the macro button is active.
 };
 
+} // namespace
+
 // ------------------------------------------------------------------------
 // Forward Declarations (for static qualifier)
 // ------------------------------------------------------------------------