pgsql: pg_dump: store unused attribs as NULL instead of '\0'

pg_dump: store unused attribs as NULL instead of '\0'

Commit f831d4accda0 changed pg_dump to emit (and pg_restore to
understand) NULLs for unused members in ArchiveEntry structs, as a side
effect of some code beautification. That broke pg_restore of dumps
generated with older pg_dump, however, so it was reverted in
19455c9f5606. Since the archiver version number has been bumped in
3b925e905de3, we can put it back.

Author: Dmitry Dolgov
Discussion: https://postgr.es/m/CA+q6zcXx0XHqLsFJLaUU2j5BDiBAHig=YRoBC_YVq7VJGvzBEA@mail.gmail.com

Branch
------
master

Details
-------
https://git.postgresql.org/pg/commitdiff/7fcdb5e002145ec95b2bebb4c125751be66c4d1a

Modified Files
--------------
src/bin/pg_dump/pg_backup_archiver.c | 11 +++----
src/bin/pg_dump/pg_backup_archiver.h | 7 +----
src/bin/pg_dump/pg_dump.c | 56 ++++++------------------------------
3 files changed, 16 insertions(+), 58 deletions(-)