Fall back to env before using static defaults

pylib/gyp/generator/make.py

Index: pylib/gyp/generator/make.py
diff --git a/pylib/gyp/generator/make.py b/pylib/gyp/generator/make.py
index b7da768fb33f5a8e12ec6ffa4c20e2fc6c1434e8..91f3df77f0bcbda6a4903d8b2ddafc1c32aa5a61 100644
--- a/pylib/gyp/generator/make.py
+++ b/pylib/gyp/generator/make.py
@@ -2063,10 +2063,10 @@ def GenerateOutput(target_list, target_dicts, data, params):
     '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])