pgsql: Replace XLOG_INCLUDE_XID flag with a more localized flag.

Replace XLOG_INCLUDE_XID flag with a more localized flag.

Commit 0bead9af484c introduced XLOG_INCLUDE_XID flag to indicate that the
WAL record contains subXID-to-topXID association. It uses that flag later
to mark in CurrentTransactionState that top-xid is logged so that we
should not try to log it again with the next WAL record in the current
subtransaction. However, we can use a localized variable to pass that
information.

In passing, change the related function and variable names to make them
consistent with what the code is actually doing.

Author: Dilip Kumar
Reviewed-by: Alvaro Herrera, Amit Kapila
Discussion: https://postgr.es/m/E1mSoYz-0007Fh-D9@gemulon.postgresql.org

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/71db6459e6e4ef623e98f3b1e3e9fed1bfb0ae3b

Modified Files
--------------
src/backend/access/transam/xact.c | 103 ++++++++++++++++----------------
src/backend/access/transam/xlog.c | 13 +++-
src/backend/access/transam/xloginsert.c | 26 ++++----
src/include/access/xact.h | 4 +-
src/include/access/xlog.h | 4 +-
5 files changed, 82 insertions(+), 68 deletions(-)