Setup ddb on all platforms. On full install it will save the dump, on NanoBSD it will print to console and auto-reboot.This way, a router running NanoBSD won't sit at a db> prompt indefinitely if it crashes.
Run dumpon earlier, split dumpon/ddb from savecore and run savecore later.
Setup textdumps too while we're at it. Handy.
Fix exec bits on rc.dumpon
Add support for dumpon/savecore to run on full installs.