bpo-36142: Exclude coreconfig.h from Py_LIMITED_API (GH-12111)

The whole coreconfig.h header is now excluded from Py_LIMITED_API.
Move functions definitions into a new internal pycore_coreconfig.h
header.

* Move Include/coreconfig.h to Include/cpython/coreconfig.h
* coreconfig.h header is now excluded from Py_LIMITED_API
* Move functions to pycore_coreconfig.h
diff --git a/Makefile.pre.in b/Makefile.pre.in
index 1c536f8..9c2d3d6 100644
--- a/Makefile.pre.in
+++ b/Makefile.pre.in
@@ -994,7 +994,6 @@
 		$(srcdir)/Include/codecs.h \
 		$(srcdir)/Include/compile.h \
 		$(srcdir)/Include/complexobject.h \
-		$(srcdir)/Include/coreconfig.h \
 		$(srcdir)/Include/descrobject.h \
 		$(srcdir)/Include/dictobject.h \
 		$(srcdir)/Include/dtoa.h \
@@ -1071,6 +1070,7 @@
 		$(srcdir)/Include/Python-ast.h \
 		\
 		$(srcdir)/Include/cpython/abstract.h \
+		$(srcdir)/Include/cpython/coreconfig.h \
 		$(srcdir)/Include/cpython/dictobject.h \
 		$(srcdir)/Include/cpython/object.h \
 		$(srcdir)/Include/cpython/objimpl.h \
@@ -1085,6 +1085,7 @@
 		$(srcdir)/Include/internal/pycore_ceval.h \
 		$(srcdir)/Include/internal/pycore_condvar.h \
 		$(srcdir)/Include/internal/pycore_context.h \
+		$(srcdir)/Include/internal/pycore_coreconfig.h \
 		$(srcdir)/Include/internal/pycore_fileutils.h \
 		$(srcdir)/Include/internal/pycore_getopt.h \
 		$(srcdir)/Include/internal/pycore_gil.h \