Fix Mascaret and Courlis for gfortran debug of Scibian 11 (gfortran 10.2.1)

Fix some problem of non initialized variables producing error at execution of some test-cases (courlis/Canal_equilibre/vnv_channel.py, python3/mascaret_cas/vnv_convert_all_cour_xcas_cas_exe.py, mascaret/Test20/vnv_test20.py, mascaret/Test21/vnv_test21.py, mascaret/Test23/vnv_test23.py, mascaret/Test24/vnv_test24.py, python3/mascaret_cas/vnv_convert_all_masc_xcas_cas_exe.py, python3/mascaret_cas/vnv_mascaret_xcas_cas_exe.py)

Validation on Mascaret and Courlis tags have been done on Scibian 11 gfortran debug