Adjust the header size calculations.
Adjust the header size calculations.

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