test: `wasi_threads_exit_*main_wasi.wat` fails on Wasmtime

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When running the wasi_threads_exit_main_wasi.wat test, Wasmtime rejects the poll_oneoff call as invalid. I extracted a replication to this Wasmtime PR: bytecodealliance/wasmtime#5891. I do not claim to understand all of the intricacies of poll_oneoff, but could it be that the parameters passed to it are incorrect in the test?

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cc: @yamt

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This also seems to be a problem with wasi_threads_exit_nonmain_wasi.wat. The original test failure (not my extracted poll_oneff) can be reproduced with:

$ RUST_LOG=trace target/release/wasmtime --wasm-features=threads --wasi-modules=experimental-wasi-threads crates/wasi-threads/tests/wasi-threads/test/testsuite/wasi_threads_exit_nonmain_wasi.wat
...
 TRACE wasmtime_wasi_threads                     > new thread requested via `wasi::thread_spawn` call
 TRACE wasi_common::snapshots::preview_1::wasi_snapshot_preview1 > wiggle abi; module="wasi_snapshot_preview1" function="poll_oneoff"
 TRACE tracing::span::active                                     > -> wiggle abi;
 TRACE wasi_common::snapshots::preview_1::wasi_snapshot_preview1 > in_=*guest 0x64 out=*guest 0xc8 nsubscriptions=1
 TRACE wasi_common::snapshots::preview_1::wasi_snapshot_preview1 > result=Err(Error { inner: Inval })
 TRACE tracing::span::active                                     > <- wiggle abi;
 TRACE tracing::span                                             > -- wiggle abi;
...