Make the `uv_fs_realpath()` binding (which calls the libc `realpath()`
on UNIX and `GetFinalPathNameByHandle()` on Windows) available as the
`fs.realpath.native()` and `fs.realpathSync.native()` functions.

The binding was already available as `process.binding('fs').realpath`
but was not exposed or tested - and partly broken as a result.

Fixes: #8715
PR-URL: #15776
Refs: #7899
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Jeremiah Senkpiel <fishrock123@rocketmail.com>
Reviewed-By: Minwoo Jung <minwoo@nodesource.com>
Reviewed-By: Trevor Norris <trev.norris@gmail.com>

Notable changes:

* **crypto**:
  - Support building with both 1.1.0 and 1.0.2 (David Benjamin) #16130
* **fs**:
  - fs.realpathSync.native and fs.realpath.native are now exposed (Ben Noordhuis) #15776
* **process**:
  - expose process.ppid (cjihrig) #16839

PR-URL: #16992

Notable changes:

* **crypto**:
  - Support building with both 1.1.0 and 1.0.2 (David Benjamin) #16130
* **fs**:
  - fs.realpathSync.native and fs.realpath.native are now exposed (Ben Noordhuis) #15776
* **process**:
  - expose process.ppid (cjihrig) #16839

PR-URL: #16992

Notable changes:

* **crypto**:
  - Support building with both 1.1.0 and 1.0.2 (David Benjamin) #16130
* **fs**:
  - fs.realpathSync.native and fs.realpath.native are now exposed (Ben Noordhuis) #15776
* **process**:
  - expose process.ppid (cjihrig) #16839

PR-URL: #16992

Notable changes:

* **crypto**:
  - Support building with both 1.1.0 and 1.0.2 (David Benjamin) #16130
* **fs**:
  - fs.realpathSync.native and fs.realpath.native are now exposed (Ben Noordhuis) #15776
* **process**:
  - expose process.ppid (cjihrig) #16839

PR-URL: #16992