sys: Remove $FreeBSD$: one-line .c comment pattern

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

Add assembly optimized code for OpenSSL on powerpc, powerpc64 and powerpc64le

Summary:
1. https://github.com/openssl/openssl/commit/34ab13b7d8e3e723adb60be8142e38b7c9cd382a
needs to be merged for ELFv2 support on big-endian.
2. crypto/openssl/crypto/ppccap.c needs to be patched.
Same reason as in https://github.com/openssl/openssl/pull/17082.

Approved by: jkim, jhibbits
MFC after: 1 month
Differential Revision: https://reviews.freebsd.org/D33076