[Libguestfs] (no subject)

[Gabriele Cerami]

Hi, we needed these changes when we had to build a guest image
compatible with a starting guest image but not backed by it in any way•
We needed some tool to check our progress, comparing original and•
rebuilt (from scratch) images, and virt-diff seemed the best option, but•
we had to soften the comparison to reduce the noise in the output. I
added some options to ignore certain informations when comparing. I
built and tested it, and now for example, one can ignore file permission
with --no-compare-perms, and still see permissions shown when files
differ by other criterias.