Import the wrapper script from zstdgrep (written by wiz@netbsd.org)
Modify it to support more than just zstd (adding support for gzip,
lzma, xz and bzip2)
Write a simple manpage dedicated for it.
Only use that new wrapper both for gnu grep and bsd grep
Next step will be removing code related to compression format from bsdgrep
Reviewed by: kevans
Approved by: kevans
MFC after: 1 week
Differential Revision: https://reviews.freebsd.org/D15193
Among new things it is now threaded by default, use zstd -T# to chose the
number of threads not that -T0 will automatically determine the number of
threads based on the number of CPU online.
