Remove $FreeBSD$: one-line sh pattern

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

libc: Remove _get_tp() and _set_tp().

Their uses have been replaced by _tcb_get() and _tcb_set() from
<machine/tls.h>.

Reviewed by: kib, jrtc27
Sponsored by: The University of Cambridge, Google Inc.
Differential Revision: https://reviews.freebsd.org/D33354

libc: add _get_tp() private function

which returns pointer to tcb

Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Differential revision: https://reviews.freebsd.org/D29623

Reduce code duplication between powerpc and powerpcspe

They're nearly identical except for a few files.
Reported by: kib