refactor: enable lint unsafe_op_in_unsafe_fn #39

Job	Run time
macos	1m 37s
minver	11s
rust_stable	52s
linux_native_builds (x86_64-unknown-linux-gnu)	1m 6s
linux_native_builds (x86_64-unknown-linux-musl)	1m 8s
rustfmt	13s
tier3 (x86_64-unknown-dragonfly)	1m 46s
tier3 (x86_64-unknown-openbsd)	54s
tier3 (armv7-unknown-linux-uclibceabihf)	58s
tier3 (x86_64-unknown-haiku)	1m 11s
redox	54s
cross_compiling (aarch64-linux-android)	34s
cross (arm-unknown-linux-gnueabi)	1m 33s
cross_compiling (arm-linux-androideabi)	42s
cross (armv7-unknown-linux-gnueabihf)	1m 32s
cross (i686-unknown-linux-gnu)	2m 25s
cross_compiling (armv7-linux-androideabi)	34s
cross (i686-unknown-linux-musl)	2m 14s
cross_compiling (i686-linux-android)	52s
cross (mips-unknown-linux-gnu)	3m 3s
cross_compiling (x86_64-linux-android)	35s
cross (mips64-unknown-linux-gnuabi64)	2m 58s
cross_compiling (arm-unknown-linux-musleabi)	33s
cross (mips64el-unknown-linux-gnuabi64)	1m 36s
cross_compiling (x86_64-unknown-fuchsia)	23s
cross_compiling (x86_64-unknown-illumos)	38s
cross (mipsel-unknown-linux-gnu)	1m 35s
cross_compiling (aarch64-apple-ios, true)	24s
cross (powerpc64le-unknown-linux-gnu)	2m 39s
cross_compiling (powerpc64-unknown-linux-gnu)	34s
cross_compiling (s390x-unknown-linux-gnu)	33s
cross_compiling (x86_64-unknown-linux-gnux32)	1m 4s
cross_compiling (x86_64-unknown-netbsd)	37s
	38m 28s

Provide feedback