fc_sort: initial commit

Ordering matters in fc files; the last match wins. In builds where
many BOARD_SEPOLICY_DIRS are set, the order of that list becomes
increasingly important in order to maintain a cohesive built
file_contexts.

To correct this, we sort the device specific file_contexts entries
with the upstream fc_sort tool.

Change-Id: Id79cc6f434c41179d5c0d0d739c4718918b0b1dc
Signed-off-by: William Roberts <william.c.roberts@intel.com>