Fixed some clang warnings

src/libslic3r/SupportMaterial.cpp

@@ -3304,7 +3304,7 @@ void PrintObjectSupportMaterial::generate_toolpaths(
 
     // Now modulate the support layer height in parallel.
     tbb::parallel_for(tbb::blocked_range<size_t>(n_raft_layers, support_layers.size()),
-        [this, &support_layers, &layer_caches]
+        [&support_layers, &layer_caches]
             (const tbb::blocked_range<size_t>& range) {
         for (size_t support_layer_id = range.begin(); support_layer_id < range.end(); ++ support_layer_id) {
             SupportLayer &support_layer = *support_layers[support_layer_id];