* lisp/progmodes/asm-mode.el: The value of fill-prefix ought to be nil
not "\t" so that fill-context-prefix can do its thing. In fact,
fill-prefix does not have to be set at all becuase asm-mode derives
from prog-mode and fill-prefix is set in simple.el.
* test/lisp/progmodes/asm-mode-tests.el: Add relevant test (bug#41064).
Copyright-paperwork-exempt: yes
* lisp/progmodes/asm-mode.el: Use lexical-binding.
(asm-comment-char): Remove redundant :group arg.
(asm-mode): Use `setq-local'.
(asm-calculate-indentation): Remove moot `or'.
* test/lisp/progmodes/asm-mode-tests.el: New file with tests for
asm-mode.el.
