[Libguestfs] [PATCH 0/2] Fix btrfs blocksize and bind mkfs.btrfs (RHBZ#807905).

https://bugzilla.redhat.com/show_bug.cgi?id=807905 Currently if you specify the blocksize parameter to mkfs-opts with a btrfs filesystem, then it fails, because mkfs.btrfs interprets the -b option as meaning filesystem size. The first patch fixes this by disallowing blocksize (it cannot be mapped meaningfully into btrfs parameters). The second patch adds the full /sbin/mkfs.btrfs utility to the API. We should eventually do the same for mke2fs. Rich.