devel/py-qt5-sip: Fix build with py311 (+)

The `_frame` struct was moved to an internal header, however the public API is
primarily read-only, and py-sip needs to build PyFrameObjects so still import
the internal headers.

Also sets the Py_BUILD_CORE define for py311a6, trying to restrict it to the frame header.

Inspired by:	cython repo
With hat:	kde
Sponsored by:	Netzkommune GmbH

devel/py-qt5-sip/files/patch-siplib.c

@@ -0,0 +1,15 @@
+--- siplib.c.orig	2022-02-01 13:29:23 UTC
++++ siplib.c
+@@ -20,6 +20,12 @@
+ #include <Python.h>
+ #include <datetime.h>
+ #include <frameobject.h>
++#if PY_VERSION_HEX >= 0x030b00a6
++   #ifndef Py_BUILD_CORE
++     #define Py_BUILD_CORE 1
++   #endif
++   #include "internal/pycore_frame.h"
++#endif
+
+ #include <assert.h>
+ #include <stdio.h>