pgsql: Move basebackup code to new directory src/backend/backup

Move basebackup code to new directory src/backend/backup

Reviewed by David Steele and Justin Pryzby

Discussion: http://postgr.es/m/CA+TgmoafqboATDSoXHz8VLrSwK_MDhjthK4hEpYjqf9_1Fmczw%40mail.gmail.com

Branch
------
master

Details
-------
https://git.postgresql.org/pg/commitdiff/a8c012869763c711abc9085f54b2a100b60a85fa

Modified Files
--------------
contrib/basebackup_to_shell/basebackup_to_shell.c  |  2 +-
src/backend/Makefile                               |  3 ++-
src/backend/access/transam/xlog.c                  |  2 +-
src/backend/access/transam/xlogrecovery.c          |  2 +-
src/backend/backup/Makefile                        | 30 ++++++++++++++++++++++
.../{replication => backup}/backup_manifest.c      |  6 ++---
src/backend/{replication => backup}/basebackup.c   | 12 ++++-----
.../{replication => backup}/basebackup_copy.c      |  6 ++---
.../{replication => backup}/basebackup_gzip.c      |  4 +--
.../{replication => backup}/basebackup_lz4.c       |  4 +--
.../{replication => backup}/basebackup_progress.c  |  6 ++---
.../{replication => backup}/basebackup_server.c    |  6 ++---
.../{replication => backup}/basebackup_sink.c      |  4 +--
.../{replication => backup}/basebackup_target.c    |  4 +--
.../{replication => backup}/basebackup_throttle.c  |  4 +--
.../{replication => backup}/basebackup_zstd.c      |  4 +--
src/backend/replication/Makefile                   | 11 --------
src/backend/replication/walsender.c                |  2 +-
src/bin/pg_basebackup/pg_basebackup.c              |  2 +-
.../{replication => backup}/backup_manifest.h      |  4 +--
src/include/{replication => backup}/basebackup.h   |  2 +-
.../{replication => backup}/basebackup_sink.h      |  2 +-
.../{replication => backup}/basebackup_target.h    |  4 +--
23 files changed, 73 insertions(+), 53 deletions(-)