[3.7] Fix misleading mentions of tp_size in comments. (GH-9136)

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/sha256module.c b/Modules/sha256module.c
index e4cb328..3599eaf 100644
--- a/Modules/sha256module.c
+++ b/Modules/sha256module.c
@@ -529,7 +529,7 @@
 static PyTypeObject SHA224type = {
     PyVarObject_HEAD_INIT(NULL, 0)
     "_sha256.sha224",   /*tp_name*/
-    sizeof(SHAobject),  /*tp_size*/
+    sizeof(SHAobject),  /*tp_basicsize*/
     0,                  /*tp_itemsize*/
     /* methods */
     SHA_dealloc,        /*tp_dealloc*/
@@ -563,7 +563,7 @@
 static PyTypeObject SHA256type = {
     PyVarObject_HEAD_INIT(NULL, 0)
     "_sha256.sha256",   /*tp_name*/
-    sizeof(SHAobject),  /*tp_size*/
+    sizeof(SHAobject),  /*tp_basicsize*/
     0,                  /*tp_itemsize*/
     /* methods */
     SHA_dealloc,        /*tp_dealloc*/