pgsql: Rename delayChkpt to delayChkptFlags.

Rename delayChkpt to delayChkptFlags.

Before commit 412ad7a55639516f284cd0ef9757d6ae5c7abd43, delayChkpt
was a Boolean. Now it's an integer. Extensions using it need to be
appropriately updated, so let's rename the field to make sure that
a hard compilation failure occurs.

Replacing delayChkpt with delayChkptFlags made a few comments extend
past 80 characters, so I reflowed them and changed some wording very
slightly.

The back-branches will need a different change to restore compatibility
with existing minor releases; this is just for master.

Per suggestion from Tom Lane.

Discussion: http://postgr.es/m/a7880f4d-1d74-582a-ada7-dad168d046d1@enterprisedb.com

Branch
------
master

Details
-------
https://git.postgresql.org/pg/commitdiff/f37015a1617d4e6b4b50a1c789b382d9a654fcd9

Modified Files
--------------
src/backend/access/transam/multixact.c | 6 +++---
src/backend/access/transam/twophase.c | 28 ++++++++++++++--------------
src/backend/access/transam/xact.c | 14 +++++++-------
src/backend/access/transam/xlog.c | 10 +++++-----
src/backend/access/transam/xloginsert.c | 2 +-
src/backend/catalog/storage.c | 6 +++---
src/backend/storage/buffer/bufmgr.c | 12 ++++++------
src/backend/storage/ipc/procarray.c | 29 +++++++++++++++--------------
src/backend/storage/lmgr/proc.c | 4 ++--
src/include/storage/proc.h | 2 +-
10 files changed, 57 insertions(+), 56 deletions(-)