One. I don't think I've ever taken an extra hit point from the FCB.
The Race/Class option for FCB is sometimes a no-brainer (extra spell known for Sorcerers, e.g.) and if for some reason I don't find the Race/Class option attractive -- a class benefit bonus of +1/2 or +1/3 may be worthwhile, but a bonus of +1/4 or +1/6 takes too long to realize -- then I take the skill point.
Usually I go "Hmm, I could have 14 CON and 10 INT, and put my favoured class bonus in skill points, or I could save an ability point AND get a bonus language by going CON 12 INT 12 and putting the FCB into HP."
Often that saved ability point goes into CON anyway and at a later level I bump my CON up to 14, ending up with the same number of skill points if I went 14 CON 10 INT but more HP and an extra language.
Granted I rarely play classes like Fighter that have such limited skill points per level, I do put my FCB into skill points with classes like that.