Add missing standard includes

src/displayapp/Messages.h

@@ -1,4 +1,5 @@
 #pragma once
+#include <cstdint>
 namespace Pinetime {
   namespace Applications {
     namespace Display {

src/displayapp/screens/BatteryIcon.h

@@ -1,4 +1,5 @@
 #pragma once
+#include <cstdint>
 
 namespace Pinetime {
   namespace Applications {

src/displayapp/screens/InfiniPaint.h

@@ -2,6 +2,7 @@
 
 #include <lvgl/lvgl.h>
 #include <cstdint>
+#include <algorithm> // std::fill
 #include "displayapp/screens/Screen.h"
 
 namespace Pinetime {