[Support] Implement is_local_impl with AIX mntctl

Authored by hubert.reinterpretcast on Mar 29 2019, 4:32 PM.


[Support] Implement is_local_impl with AIX mntctl

On AIX, we can determine whether a filesystem is remote using mntctl.

If the information is not found, then claim that the file is remote
(since that is the more restrictive case). Testing for the associated
interface is restored with a modified version of the unit test from

Reviewers: jasonliu, xingxue

Reviewed By: xingxue

Subscribers: jsji, apaprocki, Hahnfeld, zturner, krytarowski, kristina, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D58801

llvm-svn: 357333