Changes:
    3285a2dfb Workaround MSAN false-positive
    6bf128cab Assert that threads are joined before destruction
    06b72af16 Scheduler: Add a couple of asserts

Commands:
    ./third_party/update-marl.sh --squash

Bug: b/140546382
Change-Id: I8df3d233e0dd6bf2e9ebfe85bbd7630c902a6678