net/py-libnet: Update to 3.0rc1, Remove/fix BROKEN_*

Switch port to use autoplist to preclude having to manually
construct shared library names based on ARCH/uname manipulations.

While I'm here:

• Switch to latest upstream release: 3.0rc1, via CHEESESHOP
• Remove patch that was fixed upstream [1]
• Match COMMENT to setup.py:description
• Strip shared library

[1] https://github.com/allfro/pylibnet/commit/67cd7b84179def8b7d88ce1456dec3984aa9ea59

Reviewed by: loader, sbz
Approved by: sbz (maintainer)
Tested by: loader (armv6, armv7, aarch64, mips64)
MFH: 2019Q3 (blanket(s): bugfix releases, bugfixes)
Differential Revision: D20754