* Reformat fio_*() definitions for easier grep'ping
* typo
* move check_postmaster() into src/utils/file.c (from src/util.c), rename it to local_check_postmaster() and make it static/private to src/utils/file.c
* Rename pg_checksum_enable() to pg_is_checksum_enabled
* Remove unused instanceState from pg_start_backup()
* Refactor wait_wal_lsn(): remove unused pgBackup * parameter and replace InstanceState * with simple directory string
* Refactor pg_stop_backup(): remove useless conn variable
* Make some functions and variables (from backup.c) accessible from other compilation units
* Remove some references to global stream_wal variable
* Remove unused variable externaldir
* Yet another split of pg_stop_backup(): separate verification of stop_lsn into wait_wal_and_calculate_stop_lsn()
* Create pfilearray_clear_locks() helper function