updated for version 7.3.859

Problem:    'ambiwidth' must be set by the user.
Solution:   Detects East Asian ambiguous width (UAX #11) state of the terminal
            at the start-up time and 'ambiwidth' accordingly.  (Hayaki Saito)

src/main.c

@@ -804,6 +804,9 @@ vim_main2(int argc UNUSED, char **argv UNUSED)
 
     starttermcap();	    /* start termcap if not done by wait_return() */
     TIME_MSG("start termcap");
+#if defined(FEAT_TERMRESPONSE) && defined(FEAT_MBYTE)
+    may_req_ambiguous_character_width();
+#endif
 
 #ifdef FEAT_MOUSE
     setmouse();				/* may start using the mouse */