Fix command line option for reproducible summations

Actually, the "naive" (non reproducible mode) could not be used. The
code was always computing reproducible sums, which is the default.

src/utils/PugsUtils.cpp

@@ -130,7 +130,7 @@ initialize(int& argc, char* argv[])
     app.add_flag("-p,--pause-on-error", pause_on_error, "Pause for debugging on unexpected error [default: false]");
 
     bool reproducible_sums = true;
-    app.add_flag("--reproducible-sums,!--no-reproducible-sums", show_preamble,
+    app.add_flag("--reproducible-sums,!--no-reproducible-sums", reproducible_sums,
                  "Special treatment of array sums to ensure reproducibility [default: true]");
 
     app.add_flag("--parallel-output", parallel_output, "All MPI processes output to console [default: false]");