Port yuzu-emu/yuzu#4164: "hotkeys: Add a "Mute Audio" hotkey" (#5463)

Co-authored-by: Kewlan <colin_rehn@hotmail.com>

src/core/settings.cpp

@@ -131,6 +131,13 @@ void LogSettings() {
     log_setting("Debugging_GdbstubPort", values.gdbstub_port);
 }
 
+float Volume() {
+    if (values.audio_muted) {
+        return 0.0f;
+    }
+    return values.volume;
+}
+
 void LoadProfile(int index) {
     Settings::values.current_input_profile = Settings::values.input_profiles[index];
     Settings::values.current_input_profile_index = index;