Makefile.inc1: Honour DB_FROM_SRC for NO_ROOT distributeworld

Currently the host's database files are used, but on non-FreeBSD these
are not necessarily sufficient; in particular, Linux does not have a
wheel group. Instead, use -N to use the in-tree database files when
creating the METALOG entries, as is done for the recursive makes via
IMAKE_MTREE.

Reviewed by: brooks
Obtained from: CheriBSD
Differential Revision: https://reviews.freebsd.org/D35810