sw:vec-iree: Make internal model build optional

So we don't break `m simulate` for external contributors

Change-Id: I29b0b731fe74d3727634da3f7c89866b81dbde38
2 files changed
tree: 6071cc86ae075cc629c457d6daf684dee3466a0a
  1. cmake/
  2. samples/
  3. CMakeLists.txt
  4. springbok_config.h