title: 'Windows.h: No such file or directory" error when changing Platform Toolset to v140_xp
body: <p>I tried to compile an application for Windows XP; the normal executable gives the error:</p>
  <blockquote>
  <p>&quot;... is not a valid Win32 application.&quot;</p>
  </blockquote>
  <p>I read that I could create an XP-compatible executable by changing the Platform Toolset to <code>Visual Studio 2015 - Windows XP (v140_xp)</code>, but when I do that and then try to compile it gives me the following errors:</p>
  <blockquote>
  <p>Cannot open include file: 'Windows.h': No such file or directory</p>
  <p>Could not find WindowsSdkDir_71A variable from registry. TargetFrameWorkVersion or Platform toolset may be set to an invalid version number.</p>
  </blockquote>
  <p>How can I compile with this toolset version?</p>