Fix parts of issue 2249

[jimklimov]

See #2249

• Could not reproduce the autoconf problem on any of the workers, will look out for it more later.
• Fixed method declarations.
• Hacked around lack of dirent->d_type on some platforms (any non-GNU land I suppose). A better fix is desirable for fallback equivalent logic via fstat(), see e.g.
  • https://mingw-users.narkive.com/JpEGojiV/linux-dirent-d-type-windows-equivalent
  • https://stackoverflow.com/questions/35215109/struct-dirent-does-not-have-de-type-in-header-file/35215258#35215258
• Did not address the methods missing on mingw at this time.

[aquette]

spasibo for investigation and fixing @jimklimov
fstat PR would be appreciated, since I'lll be a little busy with the base devs :D

[aquette]

Faulty code fixed by removing these non portable things. This PR can be closed, though the code may serve one day...

[jimklimov]

Ref: #2251