Update the build environment to use the new GCC 9.3.0 toolchain

[karawitan]

Thanks to @extrowerk and someone@didacticode.ca,

gcc-9.3.0 is now available for bb10;

Hence we will be able to build much more ports; The wishlist is going to get hot !

Let us know on which topic you are working ...

[vaskas]

@yamsergey would be great to update the Docker image with the new toolchain 😉

[yamsergey]

Sure. But what should I do? Did anyone updated the Dockerfile which I can build?

[extrowerk]

I would recommend to test it first locally. Didacticode prooved it can build Qt, but it doesn't necessarily means it can be used as a drop-in replacement for BerryMuch.

I am far away from my desktop (again), but plan to test this after my return in early may.
Feel free to make your experiments in the meantime.