ls: exit code 2 when IOError happened for argument

[niyaznigmatullin]

• Save if an IOError happened to a file/directory that was specified in the command line as an argument. Make exit code equal to 2 in this case.
• Add exit code checking for some ls tests

$ info ls:

   Exit status:

     0 success
     1 minor problems  (e.g., failure to access a file or directory not
       specified as a command line argument.  This happens when listing a
       directory in which entries are actively being removed or renamed.)
     2 serious trouble (e.g., memory exhausted, invalid option, failure
       to access a file or directory specified as a command line argument
       or a directory loop)

GNU tests:

1. tests/ls/dangle
2. tests/ls/follow-slink
3. tests/mv/no-target-dir
   are expected to succeed after this change.

[niyaznigmatullin]

Ok, quick-xml yanked some of its versions, hope grcov releases new version soon mozilla/grcov#880

[sylvestre]

Let me ping them, I know @calixteman and @marco-c

[sylvestre]

Indeed!

Congrats! The gnu test tests/ls/dangle is no longer failing!
Congrats! The gnu test tests/ls/follow-slink is no longer failing!
Congrats! The gnu test tests/mv/no-target-dir is no longer failing!

Well spotted