sepolicy: Add cap_sys_nice to surfaceflinger

(cherry picked from commit 8f40b41e)

bug 24503801

Change-Id: I6cf1afb3982c4da4f5e57188d3e24ac01c4bd416

surfaceflinger.te

@@ -60,6 +60,9 @@ allow surfaceflinger gpu_service:service_manager { add find };
 allow surfaceflinger surfaceflinger_service:service_manager { add find };
 allow surfaceflinger window_service:service_manager find;
 
+# allow self to set SCHED_FIFO
+allow surfaceflinger self:capability sys_nice;
+
 ###
 ### Neverallow rules
 ###