Update GCC

[boxmein]

The gcc version of this project is rather old. Would you take it up to update it to gcc 5.x?
Current version:

g++ (crosstool-NG linaro-1.13.1+bzr2650 - Linaro GCC 2014.03) 4.8.3 20140303 (prerelease)

A popular library, nlohmann::json, does not support GCC 4.8.3.

[naibaf7]

I'd recommend building your own image using crosstools-ng. It takes some time but has up-to-date libraries...