Typo in xact.c

Hi hacker,

Recently, I find there might be a typo in xact.c comments.  The comments
say "PG_PROC", however, it actually means "PGPROC" structure.  Since we
have pg_proc catalog, and use PG_PROC to reference the catalog [1], so,
we should use PGPROC to reference the structure.  Any thoughts?

[1] src/include/nodes/primnodes.h

--
Regrads,
Japin Li.
ChengDu WenWu Information Technology Co.,Ltd.

diff --git a/src/backend/access/transam/README b/src/backend/access/transam/README
index 734c39a4d0..72af656060 100644
--- a/src/backend/access/transam/README
+++ b/src/backend/access/transam/README
@@ -198,7 +198,7 @@ parent.  This maintains the invariant that child transactions have XIDs later
 than their parents, which is assumed in a number of places.
 
 The subsidiary actions of obtaining a lock on the XID and entering it into
-pg_subtrans and PG_PROC are done at the time it is assigned.
+pg_subtrans and PGPROC are done at the time it is assigned.
 
 A transaction that has no XID still needs to be identified for various
 purposes, notably holding locks.  For this purpose we assign a "virtual
diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c
index 50f092d7eb..7abc6a0705 100644
--- a/src/backend/access/transam/xact.c
+++ b/src/backend/access/transam/xact.c
@@ -680,12 +680,12 @@ AssignTransactionId(TransactionState s)
         log_unknown_top = true;
 
     /*
-     * Generate a new FullTransactionId and record its xid in PG_PROC and
+     * Generate a new FullTransactionId and record its xid in PGPROC and
      * pg_subtrans.
      *
      * NB: we must make the subtrans entry BEFORE the Xid appears anywhere in
-     * shared storage other than PG_PROC; because if there's no room for it in
-     * PG_PROC, the subtrans entry is needed to ensure that other backends see
+     * shared storage other than PGPROC; because if there's no room for it in
+     * PGPROC, the subtrans entry is needed to ensure that other backends see
      * the Xid as "running".  See GetNewTransactionId.
      */
     s->fullTransactionId = GetNewTransactionId(isSubXact);