Fix build with spaces in names.

PR: 162736
Make pcengines config files compile again.
With the more generous footprints today, it makes little sense to use
UFS1 by default any more. Switch to UFS2.
Print an error message when we exit out early.

PR: 136889
Submitted by: Aragon Gouveia
When NANO_IMAGE_MBRONLY is set, and we're backing via swap, only copy
the MBR.

PR: 136889
Submitted by: Aragon Gouveia
NanoBSD has a utility shell script called save_cfg which helps keep
/cfg updated with the modified configuration files in /etc. I have
written an improved version with the following features:

* Recurses directories.
* Only requires file arguments the first time the file/directory is
* added to /cfg.
* Handles file deletions.

PR: 145962, 157533
Submitted by: Aragon Gouveia and Alex Bakhtin
Be more explicit about setting SRCCONF to /dev/null (plus allow it to
be overridden).

PR: 160443
Submitted by: Garrett Cooper