Remove $FreeBSD$: one-line sh pattern

Remove /^\s*#[#!]?\s*\$FreeBSD\$.*$\n/

revert r302146: makeroot: zero out subsecond component of time= keywords

After r345281 by mhorne subsecond components are supported.

PR: 194703
Sponsored by: The FreeBSD Foundation

makeroot.sh: allow duplicate entries even with -f <filelist>

makefs disallows duplicate entries unless the -D option is specified.

Previously makeroot.sh enabled -D unless a filelist was provided via
the -f options. The filelist logic creates an mtree manifest from the
METALOG and the provided filelist by passing them through `sort -u`,
so duplicates were not expected. However, duplicates can still occur
when a directory appears in multiple packages -- for example,

./etc/pam.d type=dir uname=root gname=wheel mode=0755
./etc/pam.d type=dir mode=0755 tags=package=runtime
./etc/pam.d type=dir mode=0755 tags=package=at
./etc/pam.d type=dir mode=0755 tags=package=ftp
./etc/pam.d type=dir mode=0755 tags=package=telnet

For the purposes of makefs these directory entries are identical, but
are of course not identical for sort -u.

For now just leave the allow duplicates -D flag enabled.

PR: 228606
Sponsored by: The FreeBSD Foundation

makeroot: zero out subsecond component of time= keywords

They are currently not supported by makefs(1).

PR: 194703
Reviewed by: brooks
Approved by: re (gjb)
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D6925

makeroot: Add -l option to set file system volume label

Reviewed by: brooks
Differential Revision: https://reviews.freebsd.org/D1782

Handle invocation with neither of -e / -f

Reviewed by: brooks
Differential Revision: https://reviews.freebsd.org/D1780

remove trailing white space...

fix spelling of unnecessary...

The -B flag is intended to take an argument.

Fix a couple typos in comments.

MFC after: 4 weeks
Sponsored by: DARPA, ARFL

Add a sample script to create filesystem images from an installed tree
created by installworld+distribution with the -DNO_ROOT option.