bpo-32430: Rename Modules/Setup.dist to Modules/Setup (GH-8229)

bpo-32430: Rename Modules/Setup.dist to Modules/Setup

Remove the necessity to copy the former manually to the latter when updating the local source tree.

sysconfig.py

@@ -36,10 +36,8 @@ if (os.name == 'nt' and
 # python_build: (Boolean) if true, we're either building Python or
 # building an extension with an un-installed Python, so we use
 # different (hard-wired) directories.
-# Setup.local is available for Makefile builds including VPATH builds,
-# Setup.dist is available on Windows
 def _is_python_source_dir(d):
-    for fn in ("Setup.dist", "Setup.local"):
+    for fn in ("Setup", "Setup.local"):
         if os.path.isfile(os.path.join(d, "Modules", fn)):
             return True
     return False