P4
The comments shown below in `access.hpp` looks wrong.
```
// * atomic_xchg: Atomically swap a new value at an address if previous value matched the compared value.
// * atomic_xchg_at: Atomically swap a new value at an internal pointer address if previous value matched the compared value.
```
And the following comment is unnecessary afterJDK-8230808.
```
The accesses that are allowed through the access.hpp file
// must be instantiated in access.cpp using the INSTANTIATE_HPP_ACCESS macro.
```
It is good to fix them.
```
// * atomic_xchg: Atomically swap a new value at an address if previous value matched the compared value.
// * atomic_xchg_at: Atomically swap a new value at an internal pointer address if previous value matched the compared value.
```
And the following comment is unnecessary after
```
The accesses that are allowed through the access.hpp file
// must be instantiated in access.cpp using the INSTANTIATE_HPP_ACCESS macro.
```
It is good to fix them.
