perf top: Improve lost events warning

Now it warns everytime that new events are lost.

And the TUI also warns now.

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-w1n168yrvrppnq6887s4u0wx@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
diff --git a/tools/perf/util/top.h b/tools/perf/util/top.h
index bfbf95b..b07b041 100644
--- a/tools/perf/util/top.h
+++ b/tools/perf/util/top.h
@@ -10,6 +10,7 @@
 
 struct perf_evlist;
 struct perf_evsel;
+struct perf_session;
 
 struct sym_entry {
 	struct rb_node		rb_node;
@@ -38,6 +39,7 @@
 	u64		   kernel_samples, us_samples;
 	u64		   exact_samples;
 	u64		   guest_us_samples, guest_kernel_samples;
+	u64		   total_lost_warned;
 	int		   print_entries, count_filter, delay_secs;
 	int		   display_weighted, freq, rb_entries;
 	pid_t		   target_pid, target_tid;
@@ -45,6 +47,7 @@
 	const char	   *cpu_list;
 	struct sym_entry   *sym_filter_entry;
 	struct perf_evsel  *sym_evsel;
+	struct perf_session *session;
 };
 
 size_t perf_top__header_snprintf(struct perf_top *top, char *bf, size_t size);