pgsql: Move connect.h from fe_utils to src/include/common.

Move connect.h from fe_utils to src/include/common.

Any libpq client can use the header.  Clients include backend components
postgres_fdw, dblink, and logical replication apply worker.  Back-patch
to v10, because another fix needs this.  In released branches, just copy
the header and keep the original.

Branch
------
REL_13_STABLE

Details
-------
https://git.postgresql.org/pg/commitdiff/41dae35532d40041297ee728eac1f4584af05570

Modified Files
--------------
contrib/oid2name/oid2name.c                | 2 +-
contrib/vacuumlo/vacuumlo.c                | 2 +-
src/bin/pg_basebackup/streamutil.c         | 2 +-
src/bin/pg_dump/pg_backup_db.c             | 2 +-
src/bin/pg_dump/pg_dump.c                  | 2 +-
src/bin/pg_dump/pg_dumpall.c               | 2 +-
src/bin/pg_rewind/libpq_fetch.c            | 2 +-
src/bin/pg_upgrade/server.c                | 2 +-
src/bin/scripts/common.c                   | 2 +-
src/bin/scripts/reindexdb.c                | 2 +-
src/bin/scripts/vacuumdb.c                 | 2 +-
src/fe_utils/cancel.c                      | 2 +-
src/include/{fe_utils => common}/connect.h | 2 +-
src/tools/findoidjoins/findoidjoins.c      | 2 +-
14 files changed, 14 insertions(+), 14 deletions(-)