Indicate support for digest init ctrl.

crypto/dsa/dsa_pmeth.c

@@ -195,6 +195,7 @@ static int pkey_dsa_ctrl(EVP_PKEY_CTX *ctx, int type, int p1, void *p2)
 		dctx->md = p2;
 		return 1;
 
+		case EVP_PKEY_CTRL_DIGESTINIT:
 		case EVP_PKEY_CTRL_PKCS7_SIGN:
 		case EVP_PKEY_CTRL_CMS_SIGN:
 		return 1;

crypto/ec/ec_pmeth.c

@@ -234,6 +234,7 @@ static int pkey_ec_ctrl(EVP_PKEY_CTX *ctx, int type, int p1, void *p2)
 
 		case EVP_PKEY_CTRL_PEER_KEY:
 		/* Default behaviour is OK */
+		case EVP_PKEY_CTRL_DIGESTINIT:
 		case EVP_PKEY_CTRL_PKCS7_SIGN:
 		case EVP_PKEY_CTRL_CMS_SIGN:
 		return 1;

crypto/rsa/rsa_pmeth.c

@@ -433,6 +433,7 @@ static int pkey_rsa_ctrl(EVP_PKEY_CTX *ctx, int type, int p1, void *p2)
 		rctx->md = p2;
 		return 1;
 
+		case EVP_PKEY_CTRL_DIGESTINIT:
 		case EVP_PKEY_CTRL_PKCS7_ENCRYPT:
 		case EVP_PKEY_CTRL_PKCS7_DECRYPT:
 		case EVP_PKEY_CTRL_PKCS7_SIGN: