Fall back to env before using static defaults

pylib/gyp/generator/make.py

 # Copyright (c) 2013 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.
 
 # Notes:
 #
 # This is all roughly based on the Makefile system used by the Linux
 # kernel, but is a non-recursive make -- we put the entire dependency
 # graph in front of make and let it figure it out.
 #
@@ skipping 2045 matching lines @@
         'link_commands': LINK_COMMANDS_AIX,
         'flock': './gyp-flock-tool flock',
         'flock_index': 2,
     })
 
   header_params.update({
     'CC.target':   GetEnvironFallback(('CC_target', 'CC'), '$(CC)'),
     'AR.target':   GetEnvironFallback(('AR_target', 'AR'), '$(AR)'),
     'CXX.target':  GetEnvironFallback(('CXX_target', 'CXX'), '$(CXX)'),
     'LINK.target': GetEnvironFallback(('LINK_target', 'LINK'), '$(LINK)'),
-    'CC.host':     GetEnvironFallback(('CC_host',), 'gcc'),
-    'AR.host':     GetEnvironFallback(('AR_host',), 'ar'),
-    'CXX.host':    GetEnvironFallback(('CXX_host',), 'g++'),
-    'LINK.host':   GetEnvironFallback(('LINK_host',), '$(CXX.host)'),
+    'CC.host':     GetEnvironFallback(('CC_host', 'CC'), 'gcc'),
+    'AR.host':     GetEnvironFallback(('AR_host', 'AR'), 'ar'),
+    'CXX.host':    GetEnvironFallback(('CXX_host', 'CXX'), 'g++'),
+    'LINK.host':   GetEnvironFallback(('LINK_host', 'LINK'), '$(CXX.host)'),
   })
 
   build_file, _, _ = gyp.common.ParseQualifiedTarget(target_list[0])
   make_global_settings_array = data[build_file].get('make_global_settings', [])
   wrappers = {}
   for key, value in make_global_settings_array:
     if key.endswith('_wrapper'):
       wrappers[key[:-len('_wrapper')]] = '$(abspath %s)' % value
   make_global_settings = ''
   for key, value in make_global_settings_array:
@@ skipping 129 matching lines @@
     root_makefile.write("endif\n")
   root_makefile.write('\n')
 
   if (not generator_flags.get('standalone')
       and generator_flags.get('auto_regeneration', True)):
     WriteAutoRegenerationRule(params, root_makefile, makefile_name, build_files)
 
   root_makefile.write(SHARED_FOOTER)
 
   root_makefile.close()