Revert "formats.c fmt_self_test_body: don't try to access salt for unsalted formats"

This reverts commit ccad62ea6af7336dbaa8a992bfd0c6e07c71eb87.

Jim's commit 4df19364e8ff265e40cbe97a626d67a5d87b23d4
(created two minutes earlier than mine) already fixed that problem.