API changes
   * Replace MBEDTLS_SHA512_NO_SHA384 config option with MBEDTLS_SHA384_C.
     This separates config option enabling the SHA384 algorithm from option
     enabling the SHA512 algorithm. Fixes #4034.
   * Introduce MBEDTLS_SHA224_C.
     This separates config option enabling the SHA224 algorithm from option
     enabling SHA256.