perf hists browser: Dynamically change verbosity level

Here is a small patch which tries to fulfill a point in the perf todo
list:

* Make pressing 'V' multiple times to go on cycling thru various
verbosity levels in 'perf top', so that info that is present in
'perf top -v' can be obtained without having to restart the tool
(acme).

After a small grep in the code, the max verbosity level seems 3; so,
we cycle at 4; I did not dare define a MAX_VERBOSE_LEVEL constant.

Signed-off-by: Alexis Berlemont <[e-mail]>
Suggested-and-Tested-by: Arnaldo Carvalho de Melo <[e-mail]>
Cc: Alexander Shishkin <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Link: http://lkml.kernel.org/r/[e-mail]
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/perf/ui/browsers/hists.c

···
 			do_zoom_dso(browser, actions);
 			continue;
 		case 'V':
-			browser->show_dso = !browser->show_dso;
+			verbose = (verbose + 1) % 4;
+			browser->show_dso = verbose > 0;
+			ui_helpline__fpush("Verbosity level set to %d\n",
+					   verbose);
 			continue;
 		case 't':
 			actions->thread = thread;

tools/perf/util/map.c

···
 			continue;
 
 		if (verbose >= 2) {
-			fputs("overlapping maps:\n", fp);
-			map__fprintf(map, fp);
-			map__fprintf(pos, fp);
+
+			if (use_browser) {
+				pr_warning("overlapping maps in %s "
+					   "(disable tui for more info)\n",
+					   map->dso->name);
+			} else {
+				fputs("overlapping maps:\n", fp);
+				map__fprintf(map, fp);
+				map__fprintf(pos, fp);
+			}
 		}
 
 		rb_erase_init(&pos->rb_node, root);
···
 
 			before->end = map->start;
 			__map_groups__insert(pos->groups, before);
-			if (verbose >= 2)
+			if (verbose >= 2 && !use_browser)
 				map__fprintf(before, fp);
 			map__put(before);
 		}
···
 
 			after->start = map->end;
 			__map_groups__insert(pos->groups, after);
-			if (verbose >= 2)
+			if (verbose >= 2 && !use_browser)
 				map__fprintf(after, fp);
 			map__put(after);
 		}