merge: bug-neomutt

 * add strndup.c strnlen.c
 * More careful file writing for aliases and attachments
 * Bye srandom() and random()
 * Don't whine if getrandom() fails.
 * Remove TLS version notification
 * Use unlocked libc IO everywhere.
 * debian: hurd build fix
 * quieten two compiler warnings
 * build tweak to allow testing
 * separate key bindings for <return> and <enter>
 * Add browser sort by description, message count and new message count