LZMA-by-default breaks compatibility with older xdelta

[bgilbert]

xdelta 3.0.11 enables LZMA secondary compression by default, which breaks compatibility with xdelta < 3.0.4 (e.g. Ubuntu 12.04), xdelta < 3.0.8 on Windows, and any newer xdelta not linked with liblzma. This is not mentioned in the release notes.

As a workaround, encoding with -S none will disable secondary compression, but that possibility is not documented in the -h output or man page.

[hurda]

And contrary to 3.1.0, there's no console-message saying that lzma is being used, not even with -v.