Add SElinux rules for /data/misc/trace

The directory is to be used in eng/userdebug build to store method
traces (previously stored in /data/dalvik-cache/profiles).

Bug: 25612377

Change-Id: Ia4365a8d1f13d33ee54115dc5e3bf62786503993
diff --git a/file_contexts b/file_contexts
index 107c73c..ffa2518 100644
--- a/file_contexts
+++ b/file_contexts
@@ -278,6 +278,7 @@
 /data/misc/perfprofd(/.*)?      u:object_r:perfprofd_data_file:s0
 /data/misc/update_engine(/.*)?  u:object_r:update_engine_data_file:s0
 /data/system/heapdump(/.*)?     u:object_r:heapdump_data_file:s0
+/data/misc/trace(/.*)?          u:object_r:method_trace_data_file:s0
 
 # Fingerprint data
 /data/system/users/[0-9]+/fpdata(/.*)? u:object_r:fingerprintd_data_file:s0