qvm-sync-clock: Do not fail if clockvm is not set
qvm-sync-clock: Do not fail if clockvm is not set

marmarek/qubes-core-admin,QubesOS/qubes-core-admin,marmarek/qubes-core-admin,QubesOS/qubes-core-admin,marmarek/qubes-core-admin,QubesOS/qubes-core-admin