Move shell entry up with other platform UID entries.

This is a trivial change to seapp_contexts to force a relabel
of /data/data directories by PMS/installd by yielding a
different hash value for comparison against /data/system/seapp_hash.
This change does not alter any actual app process or data directory
labeling decisions.  The seapp_contexts entries are sorted upon
loading by libselinux to match the precedence rules described
in the comment header, so ordering in this file should not matter.

This should not be merged before the code changes with the same Change-Id.

Change-Id: Ie440cba2c96f0907458086348197e1506d31c1b6
Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov>