wip/libxdiff 0.23 NetBSD

The LibXDiff package provides file differential library support functions. It implements basic and yet complete functionalities to create and apply file differences (patches) to both binary and text files. The library uses memory files as file abstraction to achieve both performance and portability. The proprietary output format of the binary patch file is binary and it is basically a collection of copy and insert commands. The text file differential output uses the raw unified output format (without the header).