bpo-29585: Define PYTHONFRAMEWORK in PC/pyconfig.h (#2477)

* bpo-29585: Fix PC/pyconfig.h whitespaces

Run "make patchcheck".

* bpo-29585: Define PYTHONFRAMEWORK in PC/pyconfig.h

* site: Fix path separator in _get_path() on Windows
diff --git a/Lib/site.py b/Lib/site.py
index fcf7dde..d693bc8 100644
--- a/Lib/site.py
+++ b/Lib/site.py
@@ -266,7 +266,7 @@
     version = sys.version_info
 
     if os.name == 'nt':
-        return f'{userbase}/Python{version[0]}{version[1]}/site-packages'
+        return f'{userbase}\\Python{version[0]}{version[1]}\\site-packages'
 
     if sys.platform == 'darwin' and sys._framework:
         return f'{userbase}/lib/python/site-packages'