Add a new 'Show log' extended function.
Could also be used to report last lines from log on error.

Signed-off-by: Tanguy Pruvot <tanguy.pruvot@gmail.com>

Change-Id: I3d9e51f4e81e48f20120e2449ccde651efae8d07
diff --git a/common.h b/common.h
index 77cf143..b83055e 100644
--- a/common.h
+++ b/common.h
@@ -33,6 +33,7 @@
 // The screen is small, and users may need to report these messages to support,
 // so keep the output short and not too cryptic.
 void ui_print(const char *fmt, ...) __attribute__((format(printf, 1, 2)));
+void ui_printlogtail(int nb_lines);
 
 void ui_reset_text_col();
 void ui_set_show_text(int value);