Honor $CC/$CC_host and friends in make generator.

test/compiler-override/my_cc.py

Index: test/compiler-override/my_cc.py
diff --git a/test/sanitize-rule-names/script.py b/test/compiler-override/my_cc.py
old mode 100644
new mode 100755
similarity index 79%
copy from test/sanitize-rule-names/script.py
copy to test/compiler-override/my_cc.py
index ae2efa1df46901a12301687c0c9a555b4c958260..e2f0bdd51c7c55a4aadbb2206e4d5911b23b12a2
--- a/test/sanitize-rule-names/script.py
+++ b/test/compiler-override/my_cc.py
@@ -1,10 +1,6 @@
 #!/usr/bin/env python
-
 # Copyright (c) 2012 Google Inc. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
-
-import shutil
 import sys
-
-shutil.copyfile(*sys.argv[1:])
+print sys.argv