bpo-40939: Remove the old parser (Part 2) (GH-21005)

Remove some remaining files and Makefile targets for the old parser
diff --git a/configure b/configure
index 139c2bf..dc590c2 100755
--- a/configure
+++ b/configure
@@ -2739,7 +2739,7 @@
     # If we're building out-of-tree, we need to make sure the following
     # resources get picked up before their $srcdir counterparts.
     #   Objects/ -> typeslots.inc
-    #   Include/ -> Python-ast.h, graminit.h
+    #   Include/ -> Python-ast.h
     #   Python/  -> importlib.h
     # (A side effect of this is that these resources will automatically be
     #  regenerated when building out-of-tree, regardless of whether or not