Change checksums for -h changes.

Also add completions for some new flags.
(cherry picked from commit 4dfe89a1182821da7028c933103ac3c15b410654)
add v.5.3.4 notes to DrRacket's HISTORY.txt
(cherry picked from commit 5a3a5edc9a4eab2c6723a4b31fb7d6750e2af37c)