Show explicit message when hspace fails to alloc
Show explicit message when hspace fails to alloc

Currently, in the human-readable mode, hspace doesn't show any
messages when no instances can be allocated in tiered-alloc mode. This
is confusing, so let's add an explicit message.

Signed-off-by: Iustin Pop <acf83a5274f31a43af6b914614365999469c1a31@google.com>
Reviewed-by: René Nussbaumer <bc755ac45a0e799d1d490cba76febc56d80cc5fc@google.com>

grnet/snf-ganeti,yiannist/ganeti,andir/ganeti,yiannist/ganeti,dimara/ganeti,onponomarev/ganeti,mbakke/ganeti,onponomarev/ganeti,ganeti-github-testing/ganeti-test-1,ganeti/ganeti,leshchevds/ganeti,andir/ganeti,ganeti/ganeti,grnet/snf-ganeti,leshchevds/ganeti,leshchevds/ganeti,ganeti/ganeti,apyrgio/snf-ganeti,dimara/ganeti,ganeti-github-testing/ganeti-test-1,mbakke/ganeti,bitemyapp/ganeti,apyrgio/ganeti,andir/ganeti,bitemyapp/ganeti,yiannist/ganeti,mbakke/ganeti,apyrgio/ganeti,apyrgio/snf-ganeti