tizenrt: Add release defconfig

Before updating TizenRT in build script,
I thought I would be better to maintain config files in sources.

File "config/tizenrt/release/artik05x/configs/defconfig"
is coming from "tizenrt_release_config" in travis build container:
https://hub.docker.com/r/iotjs/ubuntu/

Debug config has just been renamed, and script path adjusted.

Note for later, it would make sense to align both after upgrade.

Relate-to: jerryscript-project#1780
IoT.js-DCO-1.0-Signed-off-by: Philippe Coval p.coval@samsung.com