Only compile hsWindows.cpp on Windows

The file was ifdef'ed out on non-Windows platforms, but it sometimes
causes linker warnings about the file having no symbols. Better to just
avoid compiling/linking it entirely on non-Windows platforms.

Sources/Plasma/CoreLib/CMakeLists.txt

@@ -21,7 +21,7 @@ set(CoreLib_SOURCES
     plLoadMask.cpp
     plProduct.cpp
     plViewTransform.cpp
-    hsWindows.cpp
+    $<$<PLATFORM_ID:Windows>:hsWindows.cpp>
 )
 
 if(CMAKE_USE_WIN32_THREADS_INIT)

Sources/Plasma/CoreLib/hsWindows.cpp

@@ -40,8 +40,6 @@ You can contact Cyan Worlds, Inc. by email [email protected]
 
 *==LICENSE==*/
 
-#ifdef HS_BUILD_FOR_WIN32
-
 #include "HeadSpin.h"
 #include "hsWindows.h"
 #include <combaseapi.h>
@@ -93,5 +91,3 @@ const RTL_OSVERSIONINFOEXW& hsGetWindowsVersion()
     }
     return s_WinVer;
 }
-
-#endif