Bug#13487 Japanese data inside a comment causes the syntax error

mysql.cc:
  Fixed not to copy multibyte characters to the
  target string if we are inside a comment.

client/mysql.cc

@@ -1157,10 +1157,16 @@ static bool add_line(String &buffer,char *line,char *in_string,
 #ifdef USE_MB
     int l;
     if (use_mb(charset_info) &&
-        (l = my_ismbchar(charset_info, pos, strend))) {
+        (l= my_ismbchar(charset_info, pos, strend)))
+    {
+      if (!*ml_comment)
+      {
         while (l--)
           *out++ = *pos++;
         pos--;
+      }
+      else
+        pos+= l - 1;
       continue;
     }
 #endif