sha2.c does not compile with libressl.
sha2.c: In function 'isc_sha224_init': sha2.c:32: warning: implicit declaration of function 'EVP_MD_CTX_new' sha2.c:32: warning: assignment makes pointer from integer without a cast sha2.c: In function 'isc_sha224_invalidate': sha2.c:41: warning: implicit declaration of function 'EVP_MD_CTX_free' sha2.c: In function 'isc_sha256_init': sha2.c:80: warning: assignment makes pointer from integer without a cast sha2.c: In function 'isc_sha512_init': sha2.c:128: warning: assignment makes pointer from integer without a cast sha2.c: In function 'isc_sha384_init': sha2.c:174: warning: assignment makes pointer from integer without a cast sha2.c: In function 'isc_sha224_end': sha2.c:241: warning: implicit declaration of function 'EVP_MD_CTX_reset'