Changing the Linux SDK in the embedded platform
It only "supports" gcc 4.9.2 because that's the last version that the SDK makers actually tested. You're striking out into unknown terrirtory.

Most changes to gcc are backward-compatible, but there's always the chance that something in the SDK relies on a feature of gcc that has since been changed or removed. The only way to find out is to try it, and be prepared to debug any issues that crop up. Read the release notes, and turn on all possible warnings.

Building embedded Linux kernels is not for the faint-of-heart, especially when you start getting into the vendor-specific libraries for the special features of the board.