Don't rely on some semi-random default value.
The final `zephyr/.config` and binaries are strictly identical.
Signed-off-by: Marc Herbert <marc.herbert@intel.com>
- Create new setup() function
- Separate export for set -e compatibility
- Don't use the generic `build` directory but a more specific
`build-fuzz` instead.
- De-hardcode zephyr path thanks to west
- shellcheck clean
Signed-off-by: Marc Herbert <marc.herbert@intel.com>