fix(libkernel): share positioned transfer locks on Windows only

The per-descriptor lock exists only in the Windows transfer path, so ShareDescriptor calls SharePositionedTransfer under _WIN32 like GuestFileLockShare. Linux failed to link libkernel with an undefined reference to it.

core/libs/prx/libkernel/File/src/DescriptorControl.cpp

@@ -564,8 +564,8 @@ void ShareDescriptor(int from, int to) {
     std::lock_guard lock(g_mutex);
     auto status = Materialize(from).status;
     g_entries[to] = Entry{false, std::move(status)};
-    File::SharePositionedTransfer(from, to);
 #ifdef _WIN32
+    File::SharePositionedTransfer(from, to);
     GuestFileLockShare_nid_no_patch(from, to);
 #endif
 }