When parsing the <disk> element specification, if no <address>
is provided for the disk, then automatically assign one based on
the <target dev='sdXX'/> device name. This provides for backwards
compatability with existing applications using libvirt, while also
allowing new apps to have complete fine grained control.
* src/conf/domain_conf.h, src/conf/domain_conf.c,
src/libvirt_private.syms: Add virDomainDiskDefAssignAddress()
for assigning a controller/bus/unit address based on disk target
* src/qemu/qemu_conf.c: Call virDomainDiskDefAssignAddress() after
generating XML from ARGV
* tests/qemuxml2argvdata/*.xml: Add in drive address information
to all XML files
