pgsql: Rename CHECKPOINT_FLUSH_ALL to CHECKPOINT_FLUSH_UNLOGGED.

Rename CHECKPOINT_FLUSH_ALL to CHECKPOINT_FLUSH_UNLOGGED.

The new name more accurately relects the effects of this flag on a
requested checkpoint. Checkpoint-related log messages (i.e., those
controlled by the log_checkpoints configuration parameter) will now
say "flush-unlogged" instead of "flush-all", too. This is
preparatory work for a follow-up commit that will add a
FLUSH_UNLOGGED option to the CHECKPOINT command.

Author: Christoph Berg <myon(at)debian(dot)org>
Discussion: https://postgr.es/m/aDnaKTEf-0dLiEfz%40msg.df7cb.de

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/cd8324cc89a9f95bef9593b11507ebf2b79de72a

Modified Files
--------------
src/backend/access/transam/xlog.c | 6 +++---
src/backend/commands/dbcommands.c | 4 ++--
src/backend/storage/buffer/bufmgr.c | 6 +++---
src/include/access/xlog.h | 3 +--
4 files changed, 9 insertions(+), 10 deletions(-)