cgogn extlib : very minor changes in the IHM3 phi and alpha methods.
cgogn extlib : very minor changes in the IHM3 phi and alpha methods.

Signed-off-by: Étienne Schmitt <etienne.schmitt@inria.fr>

Former-commit-id: d717a3455aad146af98c5933c1abb2709da9fa1b
Anatoscope/sofa,FabienPean/sofa,FabienPean/sofa,Anatoscope/sofa,FabienPean/sofa,hdeling/sofa,FabienPean/sofa,Anatoscope/sofa,hdeling/sofa,Anatoscope/sofa,Anatoscope/sofa,FabienPean/sofa,FabienPean/sofa,Anatoscope/sofa,hdeling/sofa,hdeling/sofa,hdeling/sofa,hdeling/sofa,Anatoscope/sofa,hdeling/sofa,FabienPean/sofa,hdeling/sofa,FabienPean/sofa,FabienPean/sofa,Anatoscope/sofa,Anatoscope/sofa,FabienPean/sofa,hdeling/sofa,hdeling/sofa