clusapi: Use --prefer-native instead of DLL_WINE_PREATTACH.

dlls/clusapi/Makefile.in

 MODULE    = clusapi.dll
 IMPORTLIB = clusapi
 
-EXTRADLLFLAGS = -mno-cygwin
+EXTRADLLFLAGS = -mno-cygwin -Wb,--prefer-native
 
 C_SRCS = \
 	clusapi.c

dlls/clusapi/clusapi.c

@@ -115,20 +115,3 @@ DWORD WINAPI ClusterEnum(HCLUSENUM hEnum, DWORD dwIndex, LPDWORD lpdwType, LPWST
 
     return ERROR_NO_MORE_ITEMS;
 }
-
-/***********************************************************************
- *             DllMain   (CLUSAPI.@)
- *
- */
-BOOL WINAPI DllMain(HINSTANCE hinstDLL, DWORD fdwReason, LPVOID lpvReserved)
-{
-    switch(fdwReason)
-    {
-    case DLL_WINE_PREATTACH:
-        return FALSE;  /* prefer native version */
-    case DLL_PROCESS_ATTACH:
-        DisableThreadLibraryCalls( hinstDLL );
-        break;
-    }
-    return TRUE;
-}