tools: remove unnecessary imports and assignments

PR-URL: https://github.com/nodejs/node/pull/7483
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>

tools/specialize_node_d.py

@@ -7,9 +7,7 @@
 #
 
 import re
-import subprocess
 import sys
-import errno
 
 if len(sys.argv) != 5:
   print "usage: specialize_node_d.py outfile src/node.d flavor arch"