[ruby/digest] Suppress false stringop-overread warning

ruby/digest@0df846e8c1

Author: nobu

ext/digest/sha1/sha1.c

@@ -232,8 +232,14 @@ void SHA1_Update(SHA1_CTX *context, const uint8_t *data, size_t len)
     if ((j + len) > 63) {
 	(void)memcpy(&context->buffer[j], data, (i = 64-j));
 	SHA1_Transform(context->state, context->buffer);
-	for ( ; i + 63 < len; i += 64)
+	for ( ; i + 63 < len; i += 64) {
+	    RB_DIGEST_WARNING_PUSH();
+#if defined(__GNUC__) && !defined(__clang__)
+	    RB_DIGEST_WARNING_IGNORED(-Wstringop-overread);
+#endif
 	    SHA1_Transform(context->state, &data[i]);
+	    RB_DIGEST_WARNING_POP();
+	}
 	j = 0;
     } else {
 	i = 0;