perf hists: Remove hist_entry->used, not used anymore

Since hist_entry__delete() nowadays doesn't actually frees anything that
may be in use by the annotation code.

Eventually we will solve this for good by reference counting struct
symbol.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: David Ahern <dsahern@gmail.com>
Cc: Don Zickus <dzickus@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/n/tip-uldtgljymtrkns0knpiso5op@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/ui/browsers/hists.c

@@ -1731,12 +1731,7 @@ do_annotate:
 			if (!notes->src)
 				continue;
 
-			/*
-			 * Don't let this be freed, say, by hists__decay_entry.
-			 */
-			he->used = true;
 			err = hist_entry__tui_annotate(he, evsel, hbt);
-			he->used = false;
 			/*
 			 * offer option to annotate the other branch source or target
 			 * (if they exists) when returning from annotate