Fix possible memory overrun when reading broken character set files

sql/mysqld.cc:
  Safety fix.

mysys/charset.c

@@ -85,7 +85,7 @@ static my_bool get_word(struct simpleconfig_buf_st *fb, char *buf)
     endptr = fb->buf;
   }
 
-  while (!isspace(*endptr))
+  while (*endptr && !isspace(*endptr))
     *buf++= *endptr++;
   *buf=0;
   fb->p = endptr;

sql/mysqld.cc

@@ -785,7 +785,7 @@ void clean_up(bool print_message)
   if (!opt_bootstrap)
     (void) my_delete(pidfile_name,MYF(0));	// This may not always exist
 #endif
-  if (print_message)
+  if (print_message && errmesg)
     sql_print_error(ER(ER_SHUTDOWN_COMPLETE),my_progname);
   x_free((gptr) my_errmsg[ERRMAPP]);	/* Free messages */
   my_thread_end();