build: add node.exp and node.lib files to tar-headers

tools/install.py will now include the AIX node.exp and the Windows
node.lib file if they are present.

Author: gibfahn

tools/install.py

@@ -140,9 +140,13 @@ def headers(action):
   ], 'include/node/')
 
   # Add the expfile that is created on AIX
-  if sys.platform.startswith('aix'):
+  if os.isfile('out/Release/node.exp'):
     action(['out/Release/node.exp'], 'include/node/')
 
+  # Add the x64 windows libfile
+  if os.isfile('Release/node.lib'):
+    action(['Release/node.lib'], 'include/node/')
+
   subdir_files('deps/v8/include', 'include/node/', action)
 
   if 'false' == variables.get('node_shared_cares'):