Use -Oz for CORE_OPTIMIZATION_LEVEL if armclang is used. (#874)
Use -Oz for CORE_OPTIMIZATION_LEVEL if armclang is used. (#874)

* Use -Oz for CORE_OPTIMIZATION_LEVEL if armclang is used.

* Change toolchain-check to catchall else statement.

Co-authored-by: Nat Jeffries <2e09a75ee8475320aa1ac5230cf082097d8413be@gmail.com>
Co-authored-by: Ting Yan <425a412c654421fbc8df9410fe1738fe72e4ae45@users.noreply.github.com>
Co-authored-by: mergify[bot] <b09a6ee808b67e98a221404e7aaa52e0398a4954@users.noreply.github.com>
tensorflow/tflite-micro,tensorflow/tflite-micro,tensorflow/tflite-micro,tensorflow/tflite-micro