linux: fix native build after c/s 338

Index: sle10sp2-2007-12-10/mm/memory.c
===================================================================
@@ -396,9 +396,11 @@ struct page *vm_normal_page(struct vm_ar
 			return NULL;
 	}
 
+#ifdef CONFIG_XEN
 	/* XEN: Covers user-space grant mappings (even of local pages). */
 	if (unlikely(vma->vm_flags & VM_FOREIGN))
 		return NULL;
+#endif
 
 	/*
 	 * Add some anal sanity checks for now. Eventually,