pgsql: Use XLogRecPtrIsValid() in various places

Use XLogRecPtrIsValid() in various places

Now that commit 06edbed47862 has introduced XLogRecPtrIsValid(), we can
use that instead of:

- XLogRecPtrIsInvalid()
- direct comparisons with InvalidXLogRecPtr
- direct comparisons with literal 0

This makes the code more consistent.

Author: Bertrand Drouvot <bertranddrouvot(dot)pg(at)gmail(dot)com>
Discussion: https://postgr.es/m/aQB7EvGqrbZXrMlg@ip-10-97-1-34.eu-west-3.compute.internal

Branch
------
master

Details
-------
https://git.postgresql.org/pg/commitdiff/a2b02293bc65dbb2401cb19c724f52c6ee0f2faf

Modified Files
--------------
contrib/pg_walinspect/pg_walinspect.c | 4 +-
src/backend/access/gist/gist.c | 4 +-
src/backend/access/gist/gistget.c | 4 +-
src/backend/access/gist/gistutil.c | 2 +-
src/backend/access/heap/rewriteheap.c | 4 +-
src/backend/access/heap/vacuumlazy.c | 2 +-
src/backend/access/heap/visibilitymap.c | 4 +-
src/backend/access/transam/clog.c | 5 ++-
src/backend/access/transam/slru.c | 2 +-
src/backend/access/transam/timeline.c | 4 +-
src/backend/access/transam/twophase.c | 6 +--
src/backend/access/transam/xlog.c | 48 +++++++++++-----------
src/backend/access/transam/xlogbackup.c | 4 +-
src/backend/access/transam/xlogfuncs.c | 4 +-
src/backend/access/transam/xloginsert.c | 4 +-
src/backend/access/transam/xlogreader.c | 8 ++--
src/backend/access/transam/xlogrecovery.c | 20 ++++-----
src/backend/access/transam/xlogutils.c | 8 ++--
src/backend/access/transam/xlogwait.c | 2 +-
src/backend/backup/backup_manifest.c | 4 +-
src/backend/backup/basebackup_incremental.c | 2 +-
src/backend/backup/walsummary.c | 8 ++--
src/backend/catalog/pg_subscription.c | 4 +-
src/backend/commands/subscriptioncmds.c | 6 +--
src/backend/postmaster/walsummarizer.c | 18 ++++----
.../replication/logical/applyparallelworker.c | 4 +-
src/backend/replication/logical/launcher.c | 4 +-
src/backend/replication/logical/logical.c | 32 +++++++--------
src/backend/replication/logical/logicalfuncs.c | 6 +--
src/backend/replication/logical/origin.c | 18 ++++----
src/backend/replication/logical/proto.c | 18 ++++----
src/backend/replication/logical/reorderbuffer.c | 38 ++++++++---------
src/backend/replication/logical/slotsync.c | 6 +--
src/backend/replication/logical/snapbuild.c | 14 +++----
src/backend/replication/logical/worker.c | 16 ++++----
src/backend/replication/slot.c | 28 ++++++-------
src/backend/replication/slotfuncs.c | 22 +++++-----
src/backend/replication/syncrep.c | 10 ++---
src/backend/replication/walreceiver.c | 8 ++--
src/backend/replication/walreceiverfuncs.c | 2 +-
src/backend/replication/walsender.c | 30 +++++++-------
src/backend/storage/buffer/bufmgr.c | 2 +-
src/bin/pg_basebackup/pg_receivewal.c | 8 ++--
src/bin/pg_basebackup/pg_recvlogical.c | 12 +++---
src/bin/pg_rewind/pg_rewind.c | 4 +-
src/bin/pg_waldump/pg_waldump.c | 14 +++----
46 files changed, 239 insertions(+), 238 deletions(-)