remove #pragma once in cpp
remove #pragma once in cpp

rdebroiz/dtk,rdebroiz/dtk,d-tk/dtk,d-tk/dtk,NicolasSchnitzler/dtk,rdebroiz/dtk,d-tk/dtk,d-tk/dtk,d-tk/dtk,NicolasSchnitzler/dtk,d-tk/dtk,NicolasSchnitzler/dtk,rdebroiz/dtk,NicolasSchnitzler/dtk