An iSCSI device with zero hosts will result in a segmentation fault. This patch
adds a check for the number of hosts, which must be one in the case of iSCSI.
Minimal reproducing XML:
<domain type='qemu'>
<name>MyGuest</name>
<uuid>4dea22b3-1d52-d8f3-2516-782e98ab3fa0</uuid>
<os>
<type arch='x86_64'>hvm</type>
</os>
<memory>4096</memory>
<devices>
<disk type='network'>
<source name='dummy' protocol='iscsi'/>
<target dev='vda'/>
</disk>
</devices>
</domain>
Signed-off-by: Rayhan Faizel <rayhan.faizel@gmail.com>
Reviewed-by: Peter Krempa <pkrempa@redhat.com>
