fix packaging.compiler.msvc9compiler: os.environ['path'] value is also a str

Don't encode the path list
diff --git a/Lib/packaging/compiler/msvc9compiler.py b/Lib/packaging/compiler/msvc9compiler.py
index 6af0258..43fc5fa 100644
--- a/Lib/packaging/compiler/msvc9compiler.py
+++ b/Lib/packaging/compiler/msvc9compiler.py
@@ -356,8 +356,7 @@
             vc_env = query_vcvarsall(VERSION, plat_spec)
 
             # take care to only use strings in the environment.
-            self.__paths = [part.encode('mbcs') for part in
-                            vc_env['path'].split(os.pathsep)]
+            self.__paths = vc_env['path'].split(os.pathsep)
             os.environ['lib'] = vc_env['lib']
             os.environ['include'] = vc_env['include']