allowed the user to specify the value of PYTHON_EXEC

e.g. % PYTHON_EXEC=python3.1 sh run_bigtool


git-svn-id: svn://bind10.isc.org/svn/bind10/branches/f2f200910@229 e5f2f494-b856-4b98-b285-d166d9295462

src/bin/bigtool/run_bigtool

@@ -1,6 +1,6 @@
 #! /bin/sh
 
-PYTHON_EXEC=python3
+PYTHON_EXEC=${PYTHON_EXEC:-python3}
 BIGTOOL_PATH=.
 
 PYTHONPATH=../../lib/cc/python:../../lib/bigtool/