Make bsdgrep more sensitive to context overlaps. If it's printing
context that either overlaps or is immediately adjacent to another bit
of context, don't print a separator.
- Non-overlapping segments no longer have two separators between them
- Overlapping segments no longer have separators between them with
overlapping sections repeated
Submitted by: Kyle Evans <kevans91 at ksu.edu>
Reviewed by: cem
Differential Revision: https://reviews.freebsd.org/D10105