virsh: initialize str to NULL to solve a build issue

Fix a -Werror=maybe-uninitialized issue.

Signed-off-by: Chen Hanxiao <chenhanxiao@cn.fujitsu.com>
Signed-off-by: Ján Tomko <jtomko@redhat.com>
virsh: mark CPU usage field names as translatable

My commit ac75801 removed the translation markers when
moving the field names into an array.
rbd: Include return statuses from librados/librbd in logging

With this information it's easier for the user to debug what is
going wrong.
rbd: Set timeout options for librados

These timeout values make librados/librbd return -ETIMEDOUT when a
operation is blocking due to a failing/unreachable Ceph cluster.

By having the operations time out libvirt will not block.
storage conf: Add support for key-value pair options for pools

This allows the end-user to pass down options to the storage pool
backend.

For example NFS could get mount options or Ceph librados options
passed down.
storage conf: Support setting RADOS options in RBD storage backend

This way users can manually set options in librados which might suite
their needs better.
storage conf: Support mount options for NetFS pools

This way users can provide mount options for for example NFS
storage pools.
storage conf: Verify pool options and value with regex
storage conf fs: Simplify parsing options

We know that the incoming options are checked by the configuration
parser