Add --disable-page-skipping and --skip-locked to vacuumdb
DISABLE_PAGE_SKIPPING is available since v9.6, and SKIP_LOCKED since
v12. They lacked equivalents for vacuumdb, so this closes the gap.
Author: Nathan Bossart
Reviewed-by: Michael Paquier, Masahiko Sawada
Discussion: https://postgr.es/m/
FFE5373C-E26A-495B-B5C8-
911EC4A41C5E@amazon.com