Remove extra redundant work. Patch the module so behavior is the same on Unix...

Remove extra redundant work. Patch the module so behavior is the same on Unix systems even if not invoked. Tests still pass on Linux due to import protections.

setuptools/msvc9_support.py

@@ -4,7 +4,6 @@ This module improve support for Microsoft Visual C++ compilers. (Windows Only)
 import os
 import collections
 import itertools
-import platform
 import distutils.errors
 from setuptools.extern.six.moves import filterfalse
 
@@ -58,10 +57,6 @@ def patch_for_specialized_compiler():
     Microsoft Visual C++ 14.0:
         Microsoft Visual C++ Build Tools 2015 (x86, x64, arm)
     """
-    if platform.system() != 'Windows':
-        # Don't need to patch if not on Windows
-        return
-
     if 'distutils' not in globals():
         # The module isn't available to be patched
         return