debian: New upstream release

I tried to package this in your source repo but didn't figure out how to
handle the clashes (i.e. how to drop patches except to revert the
initial commit). So the repo above is git-dpm for now.

I kept
but I think that we shouldn't worry about liblzma2 since it is long
gone. Anyway, it is there. The current changelog:

| * switch to git-dpm for packaging (closes: #540405)
| * New Upstream (closes: #731634)
|  - no more "xzless error in line 49" (closes: #693537)
|  - xzgrep -h works (closes: #780268)
| * update symbol file

I built pixz against it and the internal testsuite passed. I checked out
all pristine-tar files from clamav (in the xz format) and the checkout

[ imported from uploaded NMU]