Use TryFrom for TimeSpec/Duration conversions which may underflow/overflow #1527

Job	Run time
macos	3m 29s
macos-aarch64	2m 0s
linux_native_builds (x86_64-unknown-linux-gnu)	2m 46s
minver	13s
linux_native_builds (x86_64-unknown-linux-musl)	2m 42s
rust_stable	1m 27s
rustfmt	13s
tier3 (x86_64-unknown-dragonfly)	1m 2s
tier3 (x86_64-unknown-openbsd)	1m 0s
tier3 (x86_64-unknown-haiku)	56s
tier3 (armv7-unknown-linux-uclibceabihf)	1m 13s
tier3 (i686-unknown-hurd-gnu)	56s
redox	39s
cross (arm-unknown-linux-gnueabi)	2m 3s
cross (armv7-unknown-linux-gnueabihf)	1m 48s
cross_compiling (aarch64-linux-android)	38s
cross (i686-unknown-linux-gnu)	1m 56s
cross_compiling (arm-linux-androideabi)	38s
cross (i686-unknown-linux-musl)	1m 55s
cross_compiling (armv7-linux-androideabi)	34s
cross_compiling (i686-linux-android)	40s
cross (mips-unknown-linux-gnu)	1m 55s
cross_compiling (x86_64-linux-android)	39s
cross (mips64-unknown-linux-gnuabi64)	1m 51s
cross_compiling (arm-unknown-linux-musleabi)	41s
cross (mips64el-unknown-linux-gnuabi64)	2m 1s
cross_compiling (x86_64-unknown-fuchsia)	33s
cross (mipsel-unknown-linux-gnu)	1m 50s
cross_compiling (x86_64-unknown-illumos)	33s
cross (powerpc64le-unknown-linux-gnu)	1m 52s
cross_compiling (aarch64-apple-ios, true)	36s
cross (loongarch64-unknown-linux-gnu)	1m 51s
cross_compiling (powerpc64-unknown-linux-gnu)	40s
cross_compiling (s390x-unknown-linux-gnu)	43s
cross_compiling (x86_64-unknown-linux-gnux32)	40s
cross_compiling (x86_64-unknown-netbsd)	39s
	45m 52s

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