Add a test case for doing an ECDH calculation by calling
mbedtls_ecdh_get_params on both keys, with keys belonging to
different groups. This should fail, but currently passes.
Changes include:
- Integers marked with '#' in the .function files.
- Strings should have "" in .data files.
- String comparison instead of preprocessor-like replace for e.g. '=='
- Params and variables cannot have the same name in .function files
