Packaging: remove last mentions and uses of setup.py in the code.
Now only the compatibility layer (in create, util and install) talk
about setup.py.
diff --git a/Lib/packaging/compiler/unixccompiler.py b/Lib/packaging/compiler/unixccompiler.py
index 8c24c0f..c857d03 100644
--- a/Lib/packaging/compiler/unixccompiler.py
+++ b/Lib/packaging/compiler/unixccompiler.py
@@ -33,7 +33,7 @@
# we need some way for outsiders to feed preprocessor/compiler/linker
# flags in to us -- eg. a sysadmin might want to mandate certain flags
# via a site config file, or a user might want to set something for
-# compiling this module distribution only via the setup.py command
+# compiling this module distribution only via the pysetup command
# line, whatever. As long as these options come from something on the
# current system, they can be as system-dependent as they like, and we
# should just happily stuff them into the preprocessor/compiler/linker