Fix ARM64 build error C3861: '_CountOneBits64' not found in winnt.h

The AppVeyor 'Visual Studio 2019' image update introduced Windows SDK 10.0.26100.0, which contains a bug in winnt.h where _CountOneBits64 is called without the required intrinsics being defined for the ARM64 v142 toolchain.

Including <intrin.h> in the precompiled headers (Stdafx.h) ensures the necessary intrinsic definitions are available during compilation.

Author: Luca Sonntag

CefSharp.BrowserSubprocess.Core/Stdafx.h

@@ -4,6 +4,8 @@
 
 #pragma once
 
+#include <intrin.h>
+
 #ifdef EXPORT
 #define DECL __declspec(dllexport)
 #else

CefSharp.Core.Runtime/Stdafx.h

@@ -4,6 +4,8 @@
 
 #pragma once
 
+#include <intrin.h>
+
 #ifdef EXPORT
 #define DECL __declspec(dllexport)
 #else