Remove $FreeBSD$: one-line sh pattern

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

Don't mess with BLOCKSIZE in shell startup files - it's set by login.conf(5);
there's no need to even mention it in shell rc files. Not that it's wrong;
just pointless and somewhat misleading.

Reviewed by: jilles
MFC after: 2 weeks
Sponsored by: DARPA, AFRL
Differential Revision: https://reviews.freebsd.org/D18809

Move all sh and csh files into bin/sh/ or bin/csh/

This simplifies pkgbase by migrating these to CONFS so they are properly
tagged as config files.

Approved by: will (mentor)
Differential Revision: https://reviews.freebsd.org/D16708