Update copyrights for 2020

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

src/backend/access/gist/gist.c

@@ -4,7 +4,7 @@
  *	  interface routines for the postgres GiST index 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
  *
  * IDENTIFICATION

src/backend/access/gist/gistbuild.c

@@ -4,7 +4,7 @@
  *	  build algorithm for GiST indexes 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
  *
  * IDENTIFICATION

src/backend/access/gist/gistbuildbuffers.c

@@ -4,7 +4,7 @@
  *	  node buffer management functions for GiST buffering build algorithm.
  *
  *
- * 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/gist/gistget.c

@@ -4,7 +4,7 @@
  *	  fetch tuples from a GiST scan.
  *
  *
- * 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/gist/gistproc.c

@@ -7,7 +7,7 @@
  * This gives R-tree behavior, with Guttman's poly-time split algorithm.
  *
  *
- * 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/gist/gistscan.c

@@ -4,7 +4,7 @@
  *	  routines to manage scans on GiST index relations
  *
  *
- * 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/gist/gistsplit.c

@@ -15,7 +15,7 @@
  * gistSplitByKey() is the entry point to this file.
  *
  *
- * 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/gist/gistutil.c

@@ -4,7 +4,7 @@
  *	  utilities routines for the postgres GiST index 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
  *
  * IDENTIFICATION

src/backend/access/gist/gistvacuum.c

@@ -4,7 +4,7 @@
  *	  vacuuming routines for the postgres GiST index 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
  *
  * IDENTIFICATION

src/backend/access/gist/gistvalidate.c

@@ -3,7 +3,7 @@
  * gistvalidate.c
  *	  Opclass validator for GiST.
  *
- * 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/gist/gistxlog.c

@@ -4,7 +4,7 @@
  *	  WAL replay logic for GiST.
  *
  *
- * 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