Create a tarball-based ditribution of the Mbed Crypto source code using the
code from Mbed TLS. Only export the files needed by Mbed Crypto to
implement the PSA Crypto API. Rename "mbedtls_*" and "MBEDTLS_*" symbols to
"mbedcrypto_*" and "MBEDCRYPTO_*".
The exported distribution can stand alone, without any Mbed TLS repository
needing to be present. "make test" will continue to work as before and will
run only the PSA Crypto test suite.
