include what you use in betterRenderer

Its sources reached the standard library through the project headers they
included; those are imports now. 178 headers across 56 files, plus 18 C
library headers elsewhere for memcpy/printf and friends. MSVC's STL does
not supply these transitively the way libstdc++ does.

betterRenderer/renderer/source/windshield_rain.h

@@ -1,6 +1,9 @@
 #pragma once
 
 #include "nvrenderer/nvrenderer.h"
+#include <cstddef>
+#include <cstdint>
+#include <unordered_map>
 
 struct WindshieldRain {
   void Init(NvRenderer *in_renderer);