Remove $FreeBSD$: one-line .c pattern

Remove /^[\s*]*__FBSDID\("\$FreeBSD\$"\);?\s*\n/

Remove unneeded assert.h (there is no assertion in this file).

MFC after: 2 weeks

Using results from
J. Sorenson and J. Webster, Strong pseudoprimes to twelve prime
bases, Math. Comp. 86(304):985-1003, 2017.
teach primes(6) to enumerate primes up to 2^64 - 1. Until Sorenson
and Webster's paper, we did not know how many strong speudoprime tests
were required when testing alleged primes between 3825123056546413051
and 2^64 - 1.

Reported by: Luiz Henrique de Figueiredo
Relnotes: primes(6) now enumerates primes beyond 3825123056546413050,
up to a new limit of 2^64 - 1.
MFC After: 1 week

Final step of eliminating the "games" distribution: Merge src/games
(or what's left of it, at least) into src/usr.bin.

This change will not be MFCed.

Discussed at: EuroBSDCon 2014
Committed from: EuroBSDCon 2015