Cleanup: unify struct declaration style for Python types, update names

Use struct identifiers in comments before the value.
This has some advantages:

- The struct identifiers didn't mix well with other code-comments,
  where other comments were wrapped onto the next line.
- Minor changes could re-align all other comments in the struct.
- PyVarObject_HEAD_INIT & tp_name are no longer placed on the same line.

Remove overly verbose comments copied from PyTypeObject (Python v2.x),
these aren't especially helpful and get outdated.

Also corrected some outdated names:

- PyTypeObject.tp_print -> tp_vectorcall_offset
- PyTypeObject.tp_reserved -> tp_as_async

source/blender/python/generic/imbuf_py_api.c

@@ -348,63 +348,54 @@ static Py_hash_t py_imbuf_hash(Py_ImBuf *self)
 
 PyTypeObject Py_ImBuf_Type = {
     PyVarObject_HEAD_INIT(NULL, 0)
-    /*  For printing, in format "<module>.<name>" */
-    "ImBuf",          /* tp_name */
-    sizeof(Py_ImBuf), /* int tp_basicsize; */
-    0,                /* tp_itemsize;  For allocation */
-
-    /* Methods to implement standard operations */
-
-    (destructor)py_imbuf_dealloc, /* destructor tp_dealloc; */
-    0,                            /* tp_vectorcall_offset */
-    NULL,                         /* getattrfunc tp_getattr; */
-    NULL,                         /* setattrfunc tp_setattr; */
-    NULL,                         /* cmpfunc tp_compare; */
-    (reprfunc)py_imbuf_repr,      /* reprfunc tp_repr; */
-
-    /* Method suites for standard classes */
-
-    NULL, /* PyNumberMethods *tp_as_number; */
-    NULL, /* PySequenceMethods *tp_as_sequence; */
-    NULL, /* PyMappingMethods *tp_as_mapping; */
-
-    /* More standard operations (here for binary compatibility) */
-
-    (hashfunc)py_imbuf_hash, /* hashfunc tp_hash; */
-    NULL,                    /* ternaryfunc tp_call; */
-    NULL,                    /* reprfunc tp_str; */
-    NULL,                    /* getattrofunc tp_getattro; */
-    NULL,                    /* setattrofunc tp_setattro; */
-
-    /* Functions to access object as input/output buffer */
-    NULL, /* PyBufferProcs *tp_as_buffer; */
-
-    /*** Flags to define presence of optional/expanded features ***/
-    Py_TPFLAGS_DEFAULT, /* long tp_flags; */
-
-    NULL, /*  char *tp_doc;  Documentation string */
-    /*** Assigned meaning in release 2.0 ***/
-    /* call function for all accessible objects */
-    NULL, /* traverseproc tp_traverse; */
-
-    /* delete references to contained objects */
-    NULL, /* inquiry tp_clear; */
-
-    /***  Assigned meaning in release 2.1 ***/
-    /*** rich comparisons ***/
-    NULL, /* richcmpfunc tp_richcompare; */
-
-    /***  weak reference enabler ***/
-    0, /* long tp_weaklistoffset; */
-
-    /*** Added in release 2.2 ***/
-    /*   Iterators */
-    NULL, /* getiterfunc tp_iter; */
-    NULL, /* iternextfunc tp_iternext; */
-    /*** Attribute descriptor and subclassing stuff ***/
-    Py_ImBuf_methods,   /* struct PyMethodDef *tp_methods; */
-    NULL,               /* struct PyMemberDef *tp_members; */
-    Py_ImBuf_getseters, /* struct PyGetSetDef *tp_getset; */
+    /*tp_name*/ "ImBuf",
+    /*tp_basicsize*/ sizeof(Py_ImBuf),
+    /*tp_itemsize*/ 0,
+    /*tp_dealloc*/ (destructor)py_imbuf_dealloc,
+    /*tp_vectorcall_offset*/ 0,
+    /*tp_getattr*/ NULL,
+    /*tp_setattr*/ NULL,
+    /*tp_as_async*/ NULL,
+    /*tp_repr*/ (reprfunc)py_imbuf_repr,
+    /*tp_as_number*/ NULL,
+    /*tp_as_sequence*/ NULL,
+    /*tp_as_mapping*/ NULL,
+    /*tp_hash*/ (hashfunc)py_imbuf_hash,
+    /*tp_call*/ NULL,
+    /*tp_str*/ NULL,
+    /*tp_getattro*/ NULL,
+    /*tp_setattro*/ NULL,
+    /*tp_as_buffer*/ NULL,
+    /*tp_flags*/ Py_TPFLAGS_DEFAULT,
+    /*tp_doc*/ NULL,
+    /*tp_traverse*/ NULL,
+    /*tp_clear*/ NULL,
+    /*tp_richcompare*/ NULL,
+    /*tp_weaklistoffset*/ 0,
+    /*tp_iter*/ NULL,
+    /*tp_iternext*/ NULL,
+    /*tp_methods*/ Py_ImBuf_methods,
+    /*tp_members*/ NULL,
+    /*tp_getset*/ Py_ImBuf_getseters,
+    /*tp_base*/ NULL,
+    /*tp_dict*/ NULL,
+    /*tp_descr_get*/ NULL,
+    /*tp_descr_set*/ NULL,
+    /*tp_dictoffset*/ 0,
+    /*tp_init*/ NULL,
+    /*tp_alloc*/ NULL,
+    /*tp_new*/ NULL,
+    /*tp_free*/ NULL,
+    /*tp_is_gc*/ NULL,
+    /*tp_bases*/ NULL,
+    /*tp_mro*/ NULL,
+    /*tp_cache*/ NULL,
+    /*tp_subclasses*/ NULL,
+    /*tp_weaklist*/ NULL,
+    /*tp_del*/ NULL,
+    /*tp_version_tag*/ 0,
+    /*tp_finalize*/ NULL,
+    /*tp_vectorcall*/ NULL,
 };
 
 static PyObject *Py_ImBuf_CreatePyObject(ImBuf *ibuf)