util.hashes: Expose sha224 and sha384 HMAC functions

For completeness and consistency with set of plain hash functions

util/hmac.lua

@@ -13,6 +13,8 @@ local hashes = require "util.hashes"
 return {
 	md5 = hashes.hmac_md5,
 	sha1 = hashes.hmac_sha1,
+	sha224 = hashes.hmac_sha224,
 	sha256 = hashes.hmac_sha256,
+	sha384 = hashes.hmac_sha384,
 	sha512 = hashes.hmac_sha512,
 };