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: I3775eae11bfa5905cad0d02a0bf26c76ac03437c
Signed-off-by: William Roberts <william.c.roberts@intel.com>