fix: prevent SIGURG preemption live-lock by hooking write, guarding monitor signal dispatch, and adding sigurg_handler safety net #1619

Job	Run time
test stable-aarch64-unknown-linux-gnu	22s
test nightly-x86_64-unknown-linux-gnu	4m 21s
test nightly-aarch64-unknown-linux-gnu	6m 35s
test stable-riscv64gc-unknown-linux-gnu	42s
test stable-x86_64-unknown-linux-gnu	2m 14s
test nightly-armv7-unknown-linux-gnueabihf	36s
test nightly-i686-unknown-linux-gnu	19s
test stable-i686-unknown-linux-gnu	21s
test nightly-x86_64-pc-windows-gnu	5m 23s
test stable-i686-pc-windows-msvc	4m 38s
test stable-x86_64-apple-darwin	5m 45s
test nightly-i686-pc-windows-msvc	12m 6s
test stable-x86_64-pc-windows-gnu	1s
test nightly-thumbv7neon-unknown-linux-gnueabihf	20s
test stable-i686-pc-windows-gnu	24s
test nightly-x86_64-pc-windows-msvc	12m 6s
test stable-loongarch64-unknown-linux-gnu	12m 6s
test nightly-loongarch64-unknown-linux-gnu	12m 6s
test nightly-i686-pc-windows-gnu	25s
test stable-thumbv7neon-unknown-linux-gnueabihf	5s
test stable-armv7-unknown-linux-gnueabihf	1s
test nightly-x86_64-apple-darwin	4m 52s
test nightly-riscv64gc-unknown-linux-gnu	12m 6s
test nightly-aarch64-apple-darwin	18s
test stable-aarch64-apple-darwin	19s
test stable-x86_64-pc-windows-msvc	12m 6s
	1h 50m 37s

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