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

pylib/gyp/common.py

 # 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.
 
 from __future__ import with_statement
 
 import errno
 import filecmp
 import os.path
 import re
@@ skipping 77 matching lines @@
     toolset = parsed_toolset
 
   return [build_file, target, toolset]
 
 
 def BuildFile(fully_qualified_target):
   # Extracts the build file from the fully qualified target.
   return ParseQualifiedTarget(fully_qualified_target)[0]
 
 
+def GetEnvironFallback(var_list, default):
+  """Look up a key in the environment, with fallback to secondary keys
+  and finally falling back to a default value."""
+  for var in var_list:
+    if var in os.environ:
+      return os.environ[var]
+  return default
+
+
 def QualifiedTarget(build_file, target, toolset):
   # "Qualified" means the file that a target was defined in and the target
   # name, separated by a colon, suffixed by a # and the toolset name:
   # /path/to/file.gyp:target_name#toolset
   fully_qualified = build_file + ':' + target
   if toolset:
     fully_qualified = fully_qualified + '#' + toolset
   return fully_qualified
 
 
@@ skipping 335 matching lines @@
       return
     visited.add(node)
     visiting.add(node)
     for neighbor in get_edges(node):
       Visit(neighbor)
     visiting.remove(node)
     ordered_nodes.insert(0, node)
   for node in sorted(graph):
     Visit(node)
   return ordered_nodes