Apply just the changes from the MLT branch which aren't really part of that work (#3793)

src/mbgl/renderer/render_orchestrator.cpp

@@ -428,12 +428,13 @@ std::unique_ptr<RenderTree> RenderOrchestrator::createRenderTree(
     }
 
     // Prepare. Update all matrices and generate data that we should upload to the GPU.
-    for (const auto& entry : renderSources) {
+    for (const auto& [name, renderSource] : renderSources) {
         MLN_TRACE_ZONE(prepare source);
-        if (entry.second->isEnabled()) {
-            entry.second->prepare({.transform = renderTreeParameters->transformParams,
+        if (renderSource->isEnabled()) {
+            renderSource->prepare({.transform = renderTreeParameters->transformParams,
                                    .debugOptions = updateParameters->debugOptions,
-                                   .imageManager = *imageManager});
+                                   .imageManager = *imageManager,
+                                   .sourceName = name});
         }
     }