Update copyrights for 2020

Backpatch-through: update all files in master, backpatch legal files through 9.4

src/backend/access/nbtree/nbtcompare.c

@@ -3,7 +3,7 @@
  * nbtcompare.c
  *	  Comparison functions for btree access method.
  *
- * Portions Copyright (c) 1996-2019, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  *

src/backend/access/nbtree/nbtinsert.c

@@ -3,7 +3,7 @@
  * nbtinsert.c
  *	  Item insertion in Lehman and Yao btrees for Postgres.
  *
- * Portions Copyright (c) 1996-2019, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  *

src/backend/access/nbtree/nbtpage.c

@@ -4,7 +4,7 @@
  *	  BTree-specific page management code for the Postgres btree access
  *	  method.
  *
- * Portions Copyright (c) 1996-2019, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  *

src/backend/access/nbtree/nbtree.c

@@ -8,7 +8,7 @@
  *	  This file contains only the public interface routines.
  *
  *
- * Portions Copyright (c) 1996-2019, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION

src/backend/access/nbtree/nbtsearch.c

@@ -4,7 +4,7 @@
  *	  Search code for postgres btrees.
  *
  *
- * Portions Copyright (c) 1996-2019, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION

src/backend/access/nbtree/nbtsort.c

@@ -46,7 +46,7 @@
  * This code isn't concerned about the FSM at all. The caller is responsible
  * for initializing that.
  *
- * Portions Copyright (c) 1996-2019, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION

src/backend/access/nbtree/nbtsplitloc.c

@@ -3,7 +3,7 @@
  * nbtsplitloc.c
  *	  Choose split point code for Postgres btree implementation.
  *
- * Portions Copyright (c) 1996-2019, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  *

src/backend/access/nbtree/nbtutils.c

@@ -3,7 +3,7 @@
  * nbtutils.c
  *	  Utility code for Postgres btree implementation.
  *
- * Portions Copyright (c) 1996-2019, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  *

src/backend/access/nbtree/nbtvalidate.c

@@ -3,7 +3,7 @@
  * nbtvalidate.c
  *	  Opclass validator for btree.
  *
- * Portions Copyright (c) 1996-2019, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION

src/backend/access/nbtree/nbtxlog.c

@@ -4,7 +4,7 @@
  *	  WAL replay logic for btrees.
  *
  *
- * Portions Copyright (c) 1996-2019, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION