bpo-43908: Make heap types converted during 3.10 alpha immutable (GH-26351) (GH-26766)

* Make functools types immutable

* Multibyte codec types are now immutable

* pyexpat.xmlparser is now immutable

* array.arrayiterator is now immutable

* _thread types are now immutable

* _csv types are now immutable

* _queue.SimpleQueue is now immutable

* mmap.mmap is now immutable

* unicodedata.UCD is now immutable

* sqlite3 types are now immutable

* _lsprof.Profiler is now immutable

* _overlapped.Overlapped is now immutable

* _operator types are now immutable

* winapi__overlapped.Overlapped is now immutable

* _lzma types are now immutable

* _bz2 types are now immutable

* _dbm.dbm and _gdbm.gdbm are now immutable
(cherry picked from commit 00710e6346fd2394aa020b2dfae170093effac98)

Co-authored-by: Erlend Egeberg Aasland <erlend.aasland@innova.no>

Co-authored-by: Erlend Egeberg Aasland <erlend.aasland@innova.no>
diff --git a/Modules/mmapmodule.c b/Modules/mmapmodule.c
index 8327ba6..6397b0d 100644
--- a/Modules/mmapmodule.c
+++ b/Modules/mmapmodule.c
@@ -1121,7 +1121,8 @@ static PyType_Slot mmap_object_slots[] = {
 static PyType_Spec mmap_object_spec = {
     .name = "mmap.mmap",
     .basicsize = sizeof(mmap_object),
-    .flags = (Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE | Py_TPFLAGS_HAVE_GC),
+    .flags = (Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE |
+              Py_TPFLAGS_HAVE_GC | Py_TPFLAGS_IMMUTABLETYPE),
     .slots = mmap_object_slots,
 };