Fix the parsing of HelO2 dives lacking the additional 12 byte block.
Fix the parsing of HelO2 dives lacking the additional 12 byte block.

venkateshshukla/libdivecomputer,glance-/libdivecomputer,Poltsi/libdivecomputer-vms,henrik242/libdivecomputer,josh-wambua/libdivecomputer,josh-wambua/libdivecomputer,henrik242/libdivecomputer,glance-/libdivecomputer,venkateshshukla/libdivecomputer