When linking statically against parmap, one need to link with
parmap_stubs library (since it's not recorded in the cma itself).
Findlib can automatically add the required -cclib option.
Note that there may be a much better way to fix this - like,
have this -lparmap_stubs recorded in the "Extra C object files"
header of parmap.cma (like it is in parmap.cmxa).
When linking statically against parmap, one need to link with parmap_stubs library (since it's not recorded in the cma itself). Findlib can automatically add the required -cclib option.
Note that there may be a much better way to fix this - like, have this -lparmap_stubs recorded in the "Extra C object files" header of parmap.cma (like it is in parmap.cmxa).