[2.7] Fix misleading mentions of tp_size in comments (GH-9138)

Many type object initializations labeled a field "tp_size" in the
comment, but the name of that field is tp_basicsize..
(cherry picked from commit 0e0bc4e221f592f305d335faf5f8046484eb9238)

Co-authored-by: Peter Eisentraut <peter@eisentraut.org>
diff --git a/Modules/sha512module.c b/Modules/sha512module.c
index abc9021..e3733e0 100644
--- a/Modules/sha512module.c
+++ b/Modules/sha512module.c
@@ -603,7 +603,7 @@
 static PyTypeObject SHA384type = {
     PyVarObject_HEAD_INIT(NULL, 0)
     "_sha512.sha384",   /*tp_name*/
-    sizeof(SHAobject),  /*tp_size*/
+    sizeof(SHAobject),  /*tp_basicsize*/
     0,                  /*tp_itemsize*/
     /* methods */
     SHA512_dealloc,     /*tp_dealloc*/
@@ -637,7 +637,7 @@
 static PyTypeObject SHA512type = {
     PyVarObject_HEAD_INIT(NULL, 0)
     "_sha512.sha512",   /*tp_name*/
-    sizeof(SHAobject),  /*tp_size*/
+    sizeof(SHAobject),  /*tp_basicsize*/
     0,                  /*tp_itemsize*/
     /* methods */
     SHA512_dealloc,     /*tp_dealloc*/