Remove $FreeBSD$: one-line sh pattern

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

stand: Move eficom to libefi

Rename efiserialc to eficom.c and move it to libefi. Remove
loader.efi.h, since it's not needed. It's architecture independent
(though how we use it might vary). Drivers also belong in libfoo
in the boot loader: all the BIOS drivers are in i386/libi386 and
the console driver is in efi/libefi.

Sponsored by: Netflix
Reviewed by: tsoome
Differential Revision: https://reviews.freebsd.org/D40007

loader: add comconsole implementation on top of SIO protocol

Provide comconsole on top of SIO for arm platforms (x86 does use bios version).

Move sys/boot to stand. Fix all references to new location

Sponsored by: Netflix