perf ui: Introduce non-interactive ui__info_window() function

Sometimes we want just to print a message on the center of the screen,
like in 'perf top' while we wait for the minimum amount of samples to be
collected before sorting and showing them.

Also expose __ui__info_window() as an optimization for cases where such
message is to be printed while holding the ui lock.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: https://lkml.kernel.org/n/tip-uat0f89vfwl2w52kv9wzwd8a@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
diff --git a/tools/perf/ui/util.h b/tools/perf/ui/util.h
index 5e44223..4089194 100644
--- a/tools/perf/ui/util.h
+++ b/tools/perf/ui/util.h
@@ -8,6 +8,8 @@ int ui__getch(int delay_secs);
 int ui__popup_menu(int argc, char * const argv[]);
 int ui__help_window(const char *text);
 int ui__dialog_yesno(const char *msg);
+void __ui__info_window(const char *title, const char *text, const char *exit_msg);
+void ui__info_window(const char *title, const char *text);
 int ui__question_window(const char *title, const char *text,
 			const char *exit_msg, int delay_secs);