sys: Remove $FreeBSD$: one-line .h pattern

Remove /^\s*\*+\s*\$FreeBSD\$.*$\n/

Expose zlib's utility functions in Z_SOLO library when building kernel.
This allows kernel code to reuse zlib's implementation.

PR: 229763
Reviewed by: Yoshihiro Ota <ota j email ne jp>
Relnotes: yes
Differential Revision: https://reviews.freebsd.org/D21156

Allow Kernel to link in both legacy libkern/zlib and new sys/contrib/zlib,
with an eventual goal to convert all legacl zlib callers to the new zlib
version:

* Move generic zlib shims that are not specific to zlib 1.0.4 to
sys/dev/zlib.
* Connect new zlib (1.2.11) to the zlib kernel module, currently built
with Z_SOLO.
* Prefix the legacy zlib (1.0.4) with 'zlib104_' namespace.
* Convert sys/opencrypto/cryptodeflate.c to use new zlib.
* Remove bundled zlib 1.2.3 from ZFS and adapt it to new zlib and make
it depend on the zlib module.
* Fix Z_SOLO build of new zlib.

PR: 229763
Submitted by: Yoshihiro Ota <ota j email ne jp>
Reviewed by: markm (sys/dev/zlib/zlib_kmod.c)
Relnotes: yes
Differential Revision: https://reviews.freebsd.org/D19706