sys: Remove $FreeBSD$: one-line sh pattern

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

genassym.sh: Fix two minor issues found by shellcheck

o Remove redunant $ in $(( )) expression.
o Quote arg passed to work so paths with spaces, etc will work.

MFC After: 2 weeks
Reviewed by: kib
Sponsored by: Netflix
Differential Revision: https://reviews.freebsd.org/D31335

Don't prefix zero with 0x in assym.s.

The arm64 binutils only accepts 0 as an offset to the Load-Acquire Register
instructions where llvm will acceps both 0 and 0x0. The thread switching
code uses these with SCHED_ULE to block waiting for a lock to be released.
As the offset of the data to be loaded is zero this is safe, however it is
useful to keep the offset in the instruction to document what is being
loaded.

To work around this issue in binutils only generate the 0x prefix for
non-zero values.

Reported by: kan
Sponsored by: DARPA, AFRL

genassym.sh: call nm(1) with NMFLAGS.

A new jail(8) with a configuration file, to replace the work currently done
by /etc/rc.d/jail.

- Import the HEAD csup code which is the basis for the cvsmode work.

refactor code so it can run in a chroot without having to have /dev/mounted
MFC After: 1 week

Allow one to specify the AWK used in the environment(commandline).

Gawk is blowing up when run natively on the sparc64 -- leading to totally
bogus kernel values (all "0x0"). Good ole BWK awk works fine however.

brace by itself after function declaration.
Mandated by: style(9)
Pointed out by: rwatson

Improve kernel bootstrapping:
o Use objdump instead of gensetdefs(1) to build the linker sets.
o Allow overriding of nm and objdump in resp. genassym.sh and
gensetdefs.pl for non-native toolchains.

Reviewed by: arch
Perl improvements: Jos Backus <josb@cncdsl.com>, benno

Use "nm | awk ..." instead of genassym(1) to generate symbol value headers.
Symbol values are now represented using array sizes (4 arrays per symbol
so that 16-bit machines can represent 64-bit values) instead of being raw
binary values.

Reviewed by: marcel