MBEDTLS_SHA256_C macro

\def MBEDTLS_SHA256_C Enable the SHA-256 cryptographic hash algorithm. Module: library/sha256.c Caller: library/entropy.c library/md.c library/ssl_tls.c library/ssl*_client.c library/ssl*_server.c This module adds support for SHA-256. This module is required for the SSL/TLS 1.2 PRF function.