some apps (most notably Wolfenstein: The New Order) have broken multi-context
buffer usage in which one context will attempt to write to a buffer while
another context holds unflushed usage, and the unflushed context will never
flush until the buffer write completes
it's impossible to handle this scenario correctly without deadlocking,
so add some handling to try waiting and then yolo the buffer write if
a deadlock would occur
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/19141>
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