rg_system: Do not update LED if color unchanged

gpio LED isn't very costly to update, but if there's an error it can be.

Also if we ever have support for neopixel, it would be absurd to constantly send the same color.

components/retro-go/rg_system.c

@@ -82,6 +82,7 @@ static RTC_NOINIT_ATTR time_t rtcValue;
 static bool panicTraceCleared = false;
 static bool exitCalled = false;
 static uint32_t indicators;
+static rg_color_t ledColor = -1;
 static rg_stats_t statistics;
 static rg_app_t app;
 static rg_task_t tasks[8];
@@ -183,20 +184,25 @@ static void update_statistics(void)
 static void update_indicators(void)
 {
     uint32_t visibleIndicators = indicators & app.indicatorsMask;
-    rg_color_t ledColor = 0; // C_GREEN
+    rg_color_t newColor = 0; // C_GREEN
 
     if (indicators & (3 << RG_INDICATOR_CRITICAL))
-        ledColor = C_RED; // Make it flash rapidly!
+        newColor = C_RED; // Make it flash rapidly!
     else if (visibleIndicators & (1 << RG_INDICATOR_POWER_LOW))
-        ledColor = C_RED;
+        newColor = C_RED;
     else if (visibleIndicators)
-        ledColor = C_BLUE;
+        newColor = C_BLUE;
+
+    // In some cases it can be costly to update the LED status, skip if unchanged
+    if (newColor == ledColor)
+        return;
 
 #if defined(ESP_PLATFORM) && defined(RG_GPIO_LED)
     // GPIO LED doesn't support colors, so any color = on
     if (RG_GPIO_LED != GPIO_NUM_NC)
         gpio_set_level(RG_GPIO_LED, ledColor != 0);
 #endif
+    ledColor = newColor;
 }
 
 static void system_monitor_task(void *arg)