[infer][config] fix resolution of symbolic links
[infer][config] fix resolution of symbolic links

Summary: Fix the resolution of symbolic links. The previous version did not work if the path itself was not a symbolic link, but there was a symbolic link somewhere up in the path tree. For example: `path/to/file` where `file` is not a symbolic link, but `to`  is a symbolic link.

Reviewed By: jberdine

Differential Revision: D4062947

fbshipit-source-id: 394221d

xennygrimmato/infer,kageiit/infer,jvillard/infer,kageiit/infer,kageiit/infer,kageiit/infer,ropas/infer,jvillard/infer,ryoon/infer,blzq/infer,xennygrimmato/infer,xennygrimmato/infer,ropas/infer,jsachs/infer,kageiit/infer,jvillard/infer,facebook/infer,ropas/infer,blzq/infer,ryoon/infer,ryoon/infer,jvillard/infer,blzq/infer,facebook/infer,blzq/infer,facebook/infer,ropas/infer,blzq/infer,ryoon/infer,ryoon/infer,jvillard/infer,jvillard/infer,xennygrimmato/infer,jsachs/infer,ropas/infer,facebook/infer,facebook/infer,xennygrimmato/infer,jsachs/infer,jsachs/infer,facebook/infer,kageiit/infer,jvillard/infer,ryoon/infer,jsachs/infer,xennygrimmato/infer,ropas/infer,kageiit/infer,blzq/infer,xennygrimmato/infer,facebook/infer,jsachs/infer