bsdgrep: create additional tests for coverage on recent fixes
Create additional tests to cover regressions that were discovered by
PRs linked to reviews D10098, D10102, and D10104.
It is worth noting that neither bsdgrep(1) nor gnugrep(1) in the base
system currently pass all of these tests, and gnugrep(1) not quite being
up to snuff was also noted in at least one of the PRs.
PR: 175314 202022 195763 180990 197555 197531 181263 209116
Submitted by: Kyle Evans <kevans91@ksu.edu>
Reviewed by: cem, ngie, emaste
MFC after: 1 month
Differential Revision: https://reviews.freebsd.org/D10112