Fix NPE in CombinedMessageQueue.

Apparently MessageQueue gets compiled into host code sometimes,
where Process#sArgV0 won't be set.

Bug: 380325763
Bug: 380326649
Bug: 380327599
Flag: android.os.message_queue_force_legacy
Change-Id: I3f7fa6e2f5391edc50f2961a3d7a8d01fb83098c