Make mkioctls script work on Linux and MacOS

Using find -s will not work with the Linux or MacOS find command. We pipe
to sort instead since the only real requirement here is that the order
stays the same. While I am touching this file I also fixed a == construct
which is not supported by POSIX sh but appears to work on FreeBSD.

Reviewed By: imp
Approved By: jhb (mentor)
Differential Revision: https://reviews.freebsd.org/D14246