Fix various Clippy lints #446

Job	Run time
Docs	7s
Clippy	13s
Check (armv7-sony-vita-newlibeabihf)	30s
CheckTargets	1m 5s
Check (sparcv9-sun-solaris)	27s
MinimalVersions (ubuntu-latest)	21s
Check (x86_64-pc-solaris)	36s
MSRV (ubuntu-latest)	1m 27s
Nightly	23s
MinimalVersions (macos-latest)	24s
MSRV (windows-latest)	2m 1s
MinimalVersions (windows-latest)	1m 0s
Rustfmt	7s
Sanitizer (address)	59s
Test (ubuntu-latest)	40s
Sanitizer (leak)	49s
TestPoll	28s
Test (macos-latest)	41s
Sanitizer (memory)	1m 39s
TestWakerPipe	28s
Test (windows-latest)	2m 23s
Sanitizer (thread)	56s
Passed	0s
	17m 44s

Provide feedback