perf hists browser: Elide DSO column when it is set to just one DSO, ditto for threads

And also no leed to show the [.] (level: k, . for userspace) when
showing just one DSO.

Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/n/tip-4h3f6ro5o7ebepjbssxf0dd3@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/sort.c

@@ -177,7 +177,9 @@ static int hist_entry__sym_snprintf(struct hist_entry *self, char *bf,
 				       BITS_PER_LONG / 4, self->ip, o);
 	}
 
-	ret += repsep_snprintf(bf + ret, size - ret, "[%c] ", self->level);
+	if (!sort_dso.elide)
+		ret += repsep_snprintf(bf + ret, size - ret, "[%c] ", self->level);
+
 	if (self->ms.sym)
 		ret += repsep_snprintf(bf + ret, size - ret, "%s",
 				       self->ms.sym->name);

tools/perf/util/ui/browsers/hists.c

@@ -1007,12 +1007,14 @@ zoom_dso:
 zoom_out_dso:
 				ui_helpline__pop();
 				browser->hists->dso_filter = NULL;
+				sort_dso.elide = false;
 			} else {
 				if (dso == NULL)
 					continue;
 				ui_helpline__fpush("To zoom out press <- or -> + \"Zoom out of %s DSO\"",
 						   dso->kernel ? "the Kernel" : dso->short_name);
 				browser->hists->dso_filter = dso;
+				sort_dso.elide = true;
 				pstack__push(fstack, &browser->hists->dso_filter);
 			}
 			hists__filter_by_dso(self);
@@ -1024,11 +1026,13 @@ zoom_thread:
 zoom_out_thread:
 				ui_helpline__pop();
 				browser->hists->thread_filter = NULL;
+				sort_thread.elide = false;
 			} else {
 				ui_helpline__fpush("To zoom out press <- or -> + \"Zoom out of %s(%d) thread\"",
 						   thread->comm_set ? thread->comm : "",
 						   thread->pid);
 				browser->hists->thread_filter = thread;
+				sort_thread.elide = true;
 				pstack__push(fstack, &browser->hists->thread_filter);
 			}
 			hists__filter_by_thread(self);