Prevent null pointer dereference on empty input files when diff requires
a specific version.
Fix division by zero for files with long lines (> 1024) in Plan B mode
by supporting arbitrarily long lines.
Obtained from: OpenBSD (CVS Rev 1.41, 1.42)
MFC after: 1 week
- Remove $DragonFly$ tags as they are using git nowadays and VCS tags will
not help merging.
- Other changes to Copyright headers to make them consistent with other
source code, we intend to fork from this point.
Reviewed by: pfg
DragonflyBSD and install it as bsdpatch. WITH_BSD_PATCH makes it
default and installs GNU patch as gnupatch.
Submitted by: pfg
Obtained from: The DragonflyBSD Project
