Cherry pick TrueNAS revisions (alfred):

40ac13d45510c9040f076e4c0f83906716c0322b,
e9456ee45d4208f756eabb6e0c5e3c689adbb3d4,
693be6c9c9adba7ab15e426b400dc1690ad1d230:

textdump enabling script and rc.conf options.

remove debug output.

Set debug.ddb.textdump.pending=1 to catch textdumps
more often.