Remove unused enum that started conflicting with /usr/include/dirent.h on my
system.

svn path=/trunk/; revision=52142

Change-Id: Ic7ac39a16f2ca399ccb82767a215c2f250b8347e
Reviewed-on: https://code.wireshark.org/review/3475
Reviewed-by: Balint Reczey <balint@balintreczey.hu>