scsi: Fix construction of sysfs device path

The device bus value was used instead of the device target when
building the sysfs device path. Trivial.

Signed-off-by: Viktor Mihajlovski <mihajlov@linux.vnet.ibm.com>
(cherry picked from commit 2c94e00c6098662661cd67a10e982a32b6054a3c)
qemu: fix return value of qemuDomainBlockPivot on errors

If qemuMonitorBlockJob returned 0, qemuDomainBlockPivot
might return 0 even if an error occured.

https://bugzilla.redhat.com/show_bug.cgi?id=977678
(cherry picked from commit c34107dfd3a25232255e6d6f559b1306ef99bb3b)
storage: return -1 when fs pool can't be mounted

Don't reuse the return value of virStorageBackendFileSystemIsMounted.
If it's 0, we'd return it even if the mount command failed.

Also, don't report another error if it's -1, since one has already
been reported.

Introduced by 258e06c.

https://bugzilla.redhat.com/show_bug.cgi?id=981251
(cherry picked from commit 13fde7ceab556804dc6cfb3e56938fb948ffe83d)
qemu: fix double free in qemuMigrationPrepareDirect

Remove assignment of the string freed by virURIFree
to hostname, since it's not used anywhere.

Double free introduced by ddf8ad8, useless code
introduced by f03dcc5.

https://bugzilla.redhat.com/show_bug.cgi?id=977961
(cherry picked from commit 5744d96f211160d406ec0498c2f814a67d1a3fc8)