Support negative time deltas in BWE #2179

Job	Run time
lint	47s
test_wincrypto (windows-latest, stable)	2m 49s
cargo-deny (aarch64-apple-ios)	22s
test (ubuntu-latest, stable)	1m 23s
test_wincrypto (windows-latest, beta)	2m 34s
cargo-deny (aarch64-linux-android)	20s
test (ubuntu-latest, beta)	1m 25s
test_wincrypto (windows-latest, 1.71.1)	2m 31s
cargo-deny (i686-pc-windows-gnu)	23s
test (ubuntu-latest, 1.71.1)	1m 40s
cargo-deny (i686-pc-windows-msvc)	22s
test (macos-latest, stable)	1m 11s
cargo-deny (i686-unknown-linux-gnu)	22s
test (macos-latest, beta)	1m 22s
cargo-deny (wasm32-unknown-unknown)	19s
test (macos-latest, 1.71.1)	1m 11s
cargo-deny (x86_64-apple-darwin)	23s
test (windows-latest, stable)	3m 50s
cargo-deny (x86_64-apple-ios)	22s
test (windows-latest, beta)	2m 36s
cargo-deny (x86_64-pc-windows-gnu)	20s
test (windows-latest, 1.71.1)	2m 53s
cargo-deny (x86_64-pc-windows-msvc)	22s
cargo-deny (x86_64-unknown-linux-gnu)	21s
cargo-deny (x86_64-unknown-redox)	17s
	30m 25s

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