(cherry picked from commit ee3bac4cba56b51ce924f13d77b97131eec1a865)

Authored-by: Stefan Krah <skrah@bytereef.org>

gcc -Wcast-qual turns up a number of instances of casting away constness of pointers. Some of these can be safely modified, by either:

Adding the const to the type cast, as in:

-    return _PyUnicode_FromUCS1((unsigned char*)s, size);
+    return _PyUnicode_FromUCS1((const unsigned char*)s, size);

or, Removing the cast entirely, because it's not necessary (but probably was at one time), as in:

-    PyDTrace_FUNCTION_ENTRY((char *)filename, (char *)funcname, lineno);
+    PyDTrace_FUNCTION_ENTRY(filename, funcname, lineno);

These changes will not change code, but they will make it much easier to check for errors in consts
(cherry picked from commit e6be9b59a911626d6597fe148c32f0342bd2bd24)

Co-authored-by: Andy Lester <andy@petdance.com>

Automatically replace
tp_print -> tp_vectorcall_offset
tp_compare -> tp_as_async
tp_reserved -> tp_as_async

* bpo-22385: Support output separators in hex methods.

Also in binascii.hexlify aka b2a_hex.

The underlying implementation behind all hex generation in CPython uses the
same pystrhex.c implementation.  This adds support to bytes, bytearray,
and memoryview objects.

The binascii module functions exist rather than being slated for deprecation
because they return bytes rather than requiring an intermediate step through a
str object.

This change was inspired by MicroPython which supports sep in its binascii
implementation (and does not yet support the .hex methods).

https://bugs.python.org/issue22385

Cast function pointers to (void(*)(void)) before casting to (PyCFunction)
to make "warning: cast between incompatible function types" false alarm quiet.

Fix also return type for few other functions (clear, releasebuffer).

Fix invalid function cast warnings with gcc 8
for method conventions different from METH_NOARGS, METH_O and
METH_VARARGS excluding Argument Clinic generated code.

Move _PyObject_GC_TRACK() and _PyObject_GC_UNTRACK() from
Include/objimpl.h to Include/internal/pycore_object.h.

Rename Include/internal/ headers:

* pycore_hash.h -> pycore_pyhash.h
* pycore_lifecycle.h -> pycore_pylifecycle.h
* pycore_mem.h -> pycore_pymem.h
* pycore_state.h -> pycore_pystate.h

Add missing headers to Makefile.pre.in and PCbuild:

* pycore_condvar.h.
* pycore_hamt.h
* pycore_pyhash.h