misc improvements #1116

Job	Run time
build (nightly) / rust	17s
build (msrv) / rust	17s
build (stable) / rust	11s
build no_std (stable) [w/o builder] / rust	22s
build no_std (stable) / rust	17s
style (stable) / rust	19s
build no_std (stable) [Windows] / rust	1m 30s
build no_std (nightly) / rust	23s
tests with miri (nightly) / rust	1m 52s
style (nightly) / rust	22s
build no_std (msrv) / rust	24s
style (msrv) / rust	28s
	6m 42s

Provide feedback