Teach SKIP_LOCKED to psql tab completion of VACUUM and ANALYZE
This was missing since
803b130, which has introduced the option for the
user-facing VACUUM and ANALYZE.
Author: Masahiko Sawada
Discussion: https://postgr.es/m/CAD21AoD2TMdTxRhZ7WSp940V82_OAyPmgHnbi25UbbArLgA92Q@mail.gmail.com