Use built-in print() instead of print statement

In python 3 print statement is not supported, so we should use
only print() functions.

Fixes bug 1226943

Change-Id: I05f042dc247ac117f6c2823d1326a88059875b79
diff --git a/tools/install_venv.py b/tools/install_venv.py
index 1664b35..f37e0cd 100644
--- a/tools/install_venv.py
+++ b/tools/install_venv.py
@@ -56,7 +56,7 @@
 
     Also, make test will automatically use the virtualenv.
     """
-    print help
+    print(help)
 
 
 def main(argv):