Outliner: Add commented out benchmarking calls for tree rebuilding

This way you can benchmark the tree rebuilding by simply commenting out
a single line. Not that it was difficult before, but this makes it as
easy as it gets, with basically no knowledge of existing benchmarking
tools required.

source/blender/editors/space_outliner/outliner_tree.cc

@@ -41,6 +41,7 @@
 #include "BLI_fnmatch.h"
 #include "BLI_listbase.h"
 #include "BLI_mempool.h"
+#include "BLI_timeit.hh"
 #include "BLI_utildefines.h"
 
 #include "BLT_translation.h"
@@ -1698,6 +1699,10 @@ void outliner_build_tree(Main *mainvar,
     return;
   }
 
+  /* Enable for benchmarking. Starts a timer, results will be printed on function exit. */
+  // SCOPED_TIMER("Outliner Rebuild");
+  // SCOPED_TIMER_AVERAGED("Outliner Rebuild");
+
   OutlinerTreeElementFocus focus;
   outliner_store_scrolling_position(space_outliner, region, &focus);