SELinux: Add system group to thermald to avoid dac_override denial.

Change helps resolve the following denial.

avc:  denied  { dac_override } for  capability=1  scontext=u:r:thermald:s0 tcontext=u:r:thermald:s0 tclass=capability

A similar change already exists for the hammerhead policy. Future
changes might need to be added here to accommodate additional
dac_override denials that might happen beyond this change. Consult
hammerhead change Ied2293d9effb1b2d9e043e01c08b5e7be407c868 for
some additional insight.

Change-Id: Ifdf82ac0a18b50690f55d7f3ba8565777e6612e4
Signed-off-by: rpcraig <rpcraig@tycho.ncsc.mil>
diff --git a/init.mako.rc b/init.mako.rc
index 5b4ce24..f8ea748 100644
--- a/init.mako.rc
+++ b/init.mako.rc
@@ -377,7 +377,7 @@
 
 service thermald /system/bin/thermald
     class main
-    group radio
+    group radio system
 
 service mpdecision /system/bin/mpdecision --no_sleep --avg_comp
     class main