conf: use g_strdup in virDomainDiskSet
conf: use g_strdup in virDomainDiskSet

Use a temporary variable to allow copying from the
currently set source.

Always return 0 since none of the callers distinguishes
between 0 and 1 propagated from VIR_STRDUP.

Signed-off-by: Ján Tomko <4cab11cfb98d3c937327354a78eb07dbb6ee2bc6@redhat.com>
Reviewed-by: Michal Privoznik <83d82aaba2eed257f4814b0c239c260c4caaadf0@redhat.com>

crobinso/libvirt,fabianfreyer/libvirt,jardasgit/libvirt,jfehlig/libvirt,nertpinx/libvirt,jardasgit/libvirt,crobinso/libvirt,fabianfreyer/libvirt,jfehlig/libvirt,jfehlig/libvirt,zippy2/libvirt,nertpinx/libvirt,libvirt/libvirt,jfehlig/libvirt,olafhering/libvirt,crobinso/libvirt,zippy2/libvirt,crobinso/libvirt,jardasgit/libvirt,jardasgit/libvirt,libvirt/libvirt,libvirt/libvirt,jardasgit/libvirt,libvirt/libvirt,zippy2/libvirt,nertpinx/libvirt,fabianfreyer/libvirt,zippy2/libvirt,fabianfreyer/libvirt,nertpinx/libvirt,olafhering/libvirt,fabianfreyer/libvirt,olafhering/libvirt,nertpinx/libvirt,olafhering/libvirt