The part of the code meant to run inside the enclave (src/enclave/inside) is only used as an API through the ECall interface. As a consequence, no CMake target (other than enclave_trusted) would trigger the build of the trusted side, and the enclave was not getting re-built (i.e. it was not there in clean builds).

To dive in a bit deeper, enclave code (i.e. the enclave_trusted target in CMake) gets built into a signed library as a post_target command. Source code elsewhere just assumes that the library will be there at runtime (path is hardcoded).

There used to be an add_dependency in the original CMake, but I dropped it in the re-factoring process in #588.

I also fix a compilation issue that had slipped because of this.