[egs] Fix python error by moving __future__ import to top (#2405)

Author: entn-at

egs/hkust/s5/local/hkust_segment.py

@@ -1,8 +1,8 @@
 #!/usr/bin/env python
 #coding:utf-8
 
-import sys
 from __future__ import print_function
+import sys
 from mmseg import seg_txt
 for line in sys.stdin:
   blks = str.split(line)