Platform: add Direct3D11 module

This adds the Direct3D v11 module for Windows.  This is required to gain
access to the DXGI interfaces, which homes the DXGISwapChain interface.

(cherry picked from commit 86a8b1b)

Author: compnerd

stdlib/public/Platform/winsdk.modulemap

@@ -159,6 +159,14 @@ module WinSDK [system] {
   }
 
   explicit module DirectX {
+    module Direct3D11 {
+      header "d3d11.h"
+      export *
+
+      link "d3d12.lib"
+      link "dxgi.lib"
+    }
+
     module Direct3D12 {
       header "d3d12.h"
       export *