fc_sort: rectify with upstream

Code review of:
  - https://android-review.googlesource.com/#/c/platform/system/sepolicy/+/512420/

had some comments. These were addressed and upstreamed here:
  - https://github.com/TresysTechnology/refpolicy/commit/65620e0f94541195fed45f34d4fc1218b4e0d6f3



Bring these changes back into the AOSP tree.

Test: verify that output sorted device files did not change hashes when built.

Change-Id: I7f07d3f74923cf731e853629034469784fc669f7
Signed-off-by: William Roberts <william.c.roberts@intel.com>