Explicitly use CreateFileA in readlink
Explicitly use CreateFileA in readlink

Summary:
In Unicode enabled projects, this errors because CreateFile aliases
CreateFileW, which takes wchar_t* not char*.

Reviewed By: Orvid, yfeldblum

Differential Revision: D4878424

fbshipit-source-id: b44b369c0533e74163f68d95c2bf353584033731

Orvid/folly,Orvid/folly,rklabs/folly,facebook/folly,facebook/folly,facebook/folly,Orvid/folly,rklabs/folly,facebook/folly,rklabs/folly,rklabs/folly,facebook/folly,Orvid/folly,Orvid/folly,rklabs/folly