Cleanup usage of unsafe blocks #781

Job	Run time
apidiff (aws-lc-sys, branch)	2m 29s
apidiff (aws-lc-sys, published)	2m 39s
apidiff (aws-lc-fips-sys, branch)	2m 36s
bindgen-dependency (ubuntu-latest)	25s
apidiff (aws-lc-fips-sys, published)	2m 49s
bindgen-dependency (macos-12)	31s
apidiff (aws-lc-rs, branch)	2m 28s
bindgen-fips-dependency (ubuntu-latest)	19s
clippy (aws-lc-rs, --features bindgen,unstable)	1m 13s
apidiff (aws-lc-rs, published)	2m 44s
bindgen-dependency (macos-13-xlarge)	27s
clippy (aws-lc-rs, --features bindgen,unstable,fips)	1m 35s
bindgen-fips-dependency (macos-12)	28s
bindgen-dependency (windows-latest)	40s
clippy (aws-lc-rs, --no-default-features --features aws-lc-sys)	26s
bindgen-fips-dependency (macos-13-xlarge)	24s
bindgen-fips-dependency (windows-latest)	40s
copyright	8s
metadata-checks	35s
dependency-review	19s
Resolve the dependencies to the minimum SemVer version	38s
mirai-analysis	3m 6s
rustfmt	26s
semver-checks	1m 26s
udeps	7m 9s
	36m 40s

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