Make htools tolerate missing "dtotal" and "dfree" on luxi
Make htools tolerate missing "dtotal" and "dfree" on luxi

If a cluster allows sharedfile as only disk template, the amount of
total and free disk space might not be available. This is perfectly
normal, hence make the luxi backend handle it gracefully and just report
0 available disk on 0 total disk.

Signed-off-by: Klaus Aehlig <4ce51de36d9068cd7db2eec1151e0f3f95419008@google.com>
Reviewed-by: Petr Pudlak <9d19625f8ee825a2c398462ed335cbcf98f79c32@google.com>

ganeti/ganeti,yiannist/ganeti,mbakke/ganeti,leshchevds/ganeti,bitemyapp/ganeti,mbakke/ganeti,bitemyapp/ganeti,yiannist/ganeti,onponomarev/ganeti,leshchevds/ganeti,mbakke/ganeti,ganeti/ganeti,onponomarev/ganeti,yiannist/ganeti,ganeti/ganeti,grnet/snf-ganeti,andir/ganeti,andir/ganeti,grnet/snf-ganeti,andir/ganeti,leshchevds/ganeti