Clarify a progress message

Author: tbkka

Performance/runners/cpp.sh

@@ -26,13 +26,16 @@ function run_cpp_harness() {
     gen_harness_path="$script_dir/_generated/Harness+Generated.cc"
     generate_cpp_harness
 
-    echo "Building C++ test harness..."
+    echo
+    echo "Building C++ libprotobuf and performance test harness..."
+    echo
 
     pushd $script_dir/runners
     cmake -B ../_generated -S .
     cmake --build ../_generated
     popd
 
     run_harness_and_concatenate_results "C++" "$harness" "$partial_results"
+    echo
   )
 }