Support for detecting trailing non-LNK data

[wxsBSD]

Some LNK files have data appended to the end. It would be useful if liblnk could detect that there is data at the end of the file and represent it as an offset value so it can be easily carved out. a8fac75d06cf1d4e30f9b118a962a24413d046dec622bd17dd594250252543e9 is one example of a LNK with a PE appended to the end of it. While easy to find the PE I have other examples with encrypted/compressed data on the end that are not easily recognizable.