bin/bfs_tools: Fix array index is out of bounds

If length == BPLUSTREE_MAX_KEY_LENGTH at line 237,
buffer[] index may be out of bounds at line 245.
Pointed out by cppcheck.

Change-Id: Ib86abeaa72526b327af85ca9a26b050834f5a2c9
Reviewed-on: https://review.haiku-os.org/c/haiku/+/3501
Reviewed-by: Jérôme Duval <jerome.duval@gmail.com>

bfs_tools: License clarification to MIT.

* Consulted with Axel D. via IRC to confirm license desires.

bfsinfo: Added option to list/count B+tree entries.

* -l now lists the contents of string B+trees.
* -c now counts the keys in a B+tree.
* Use BPLUSTREE_MAX_KEY_LENGTH to determine the maximum allowed
key length (was hardcoded to 255 before).

bfsinfo: fixes 64 bit warnings

Imported BFS-Tools (without docs), added bfsinfo to the image.

* The sources are unchanged, and most of it doesn't follow Haiku's coding
style -- stuff that I updated over the years might also have seen a coding
style update.
* This was also the basis on which Haiku's BFS has been written.
* In the long run, the stuff in 'lib' that is already part of BFS should
be removed, and used directly from BFS itself.
* I haven't yet added any other of the tools to the image. Not sure if they
are ready for inclusion yet; 'recover' could also be renamed to reflect that
it is BFS specific.

bfsinfo: fixes 64 bit warnings

Imported BFS-Tools (without docs), added bfsinfo to the image.

* The sources are unchanged, and most of it doesn't follow Haiku's coding
style -- stuff that I updated over the years might also have seen a coding
style update.
* This was also the basis on which Haiku's BFS has been written.
* In the long run, the stuff in 'lib' that is already part of BFS should
be removed, and used directly from BFS itself.
* I haven't yet added any other of the tools to the image. Not sure if they
are ready for inclusion yet; 'recover' could also be renamed to reflect that
it is BFS specific.