Restore the protoc incantation for the working tree

Author: tbkka

Performance/perf_runner.sh

@@ -351,6 +351,11 @@ echo
 
 build_swift_packages "$script_dir/.." "ForWorkTree"
 
+${PROTOC} --plugin="$script_dir/../.build/release/protoc-gen-swift" \
+          --swift_out=FileNaming=DropPath:"$GIT_WORKTREE/Performance/_generated" \
+          --proto_path=`dirname $gen_message_path` \
+          "$gen_message_path"
+
 harness_swift="$script_dir/_generated/harness_swift"
 results_trace="$script_dir/_results/$report_type (swift)"
 display_results_trace="$results_trace"