Enable D3D12 detection when using mingw-w64 with cmake too

c.f.: autotools commit 59fb7acbf7af9d64a2d5432bb6677585a0ddd50a

CMakeLists.txt

@@ -1600,7 +1600,7 @@ elseif(WINDOWS)
       #include <winsdkver.h>
       #include <sdkddkver.h>
       #include <d3d12.h>
-      ID3D12Device5 *device;
+      ID3D12Device1 *device;
       #if WDK_NTDDI_VERSION > 0x0A000008
       int main(int argc, char **argv) { return 0; }
       #endif" HAVE_D3D12_H)