Remove unpacked cruft committed by mistake

It was also causing git lfs fsck to fail:

$ git lfs fsck
pointer: unexpectedGitObject: "doc/libexif-api.html.tar.gz" (treeish db3af8dd57be6f22710afadd47c2baf196a9affb) should have been a pointer but was not

Signed-off-by: Emanuele Aina emanuele.aina@collabora.com