Follow-up to ae7d6db1d9

Exporting G-code on a worker thread did not work correctly as the worker
threads were using user's locale, not "C" locale.
The "C" locale is newly enforced to TBB worker threads by
name_tbb_thread_pool_threads_set_locale()

src/libslic3r/SLAPrint.cpp

@@ -693,7 +693,7 @@ void SLAPrint::process()
     if (m_objects.empty())
         return;
 
-    name_tbb_thread_pool_threads();
+    name_tbb_thread_pool_threads_set_locale();
 
     // Assumption: at this point the print objects should be populated only with
     // the model objects we have to process and the instances are also filtered