Message style improvements

src/bin/initdb/initdb.c

src/bin/pg_ctl/pg_ctl.c

src/bin/pg_dump/compress_io.c

src/bin/pg_dump/dumputils.c

src/bin/pg_dump/pg_backup_directory.c

src/bin/pg_dump/pg_dump_sort.c

src/bin/pg_resetxlog/pg_resetxlog.c

src/bin/psql/command.c