Silencing external warnings during compilation

[rubens-bolgheroni]

It would be better if, during ugdk compilation, we could silence the warnings that are not ours, and are not our responsability to change it, for example, the ones from libjson

[josealvim]

One way we could do this was wrapping the external headers in another header like this

• #pragma GCC system_header
• #include STUFF
  Wil said that was horrible :l