read: improve handling of 0 for tombstones #543

Job	Run time
Build fuzz targets	1m 6s
msrv-read	3m 2s
bench	1m 15s
build (ubuntu-latest, stable)	48s
coverage	1m 7s
build (ubuntu-latest, beta)	46s
cross (i686-unknown-linux-gnu)	44s
doc	25s
build (ubuntu-latest, nightly)	43s
cross (powerpc64-unknown-linux-gnu)	55s
build (stable, macOS-latest)	43s
features	3m 4s
msrv	3m 0s
rustfmt	5s
Run `debug_abbrev` fuzz target	5m 11s
Run `debug_aranges` fuzz target	5m 6s
Run `debug_info` fuzz target	5m 6s
Run `debug_line` fuzz target	5m 10s
Run `eh_frame` fuzz target	5m 5s
Run `eh_frame_hdr` fuzz target	5m 15s
	48m 36s

Provide feedback