read: improve handling of 0 for tombstones #533

Job	Run time
bench	1m 7s
build (ubuntu-latest, stable)	40s
Build fuzz targets	1m 8s
build (ubuntu-latest, beta)	48s
coverage	1m 1s
build (ubuntu-latest, nightly)	45s
cross (i686-unknown-linux-gnu)	58s
build (stable, macOS-latest)	43s
cross (powerpc64-unknown-linux-gnu)	46s
doc	22s
features	2m 51s
msrv	2m 54s
msrv-read	2m 58s
rustfmt	4s
Run `debug_abbrev` fuzz target	5m 7s
Run `debug_aranges` fuzz target	5m 11s
Run `debug_info` fuzz target	5m 10s
Run `debug_line` fuzz target	5m 9s
Run `eh_frame` fuzz target	5m 10s
Run `eh_frame_hdr` fuzz target	5m 7s
	47m 59s

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