Allow adbd to write to /data/adb

adbd writes debugging information to /data/adb
when persist.adb.trace_mask is set. Allow it.

Bug: https://code.google.com/p/android/issues/detail?id=72895
Change-Id: Ia5af09045e9f72a95325b429c30a5ae78e104bdc
diff --git a/file_contexts b/file_contexts
index 416d783..1d81cbf 100644
--- a/file_contexts
+++ b/file_contexts
@@ -189,6 +189,7 @@
 /data/resource-cache(/.*)? u:object_r:resourcecache_data_file:s0
 /data/dalvik-cache(/.*)? u:object_r:dalvikcache_data_file:s0
 /data/dalvik-cache/profiles(/.*)? u:object_r:dalvikcache_profiles_data_file:s0
+/data/adb(/.*)?		u:object_r:adb_data_file:s0
 /data/anr(/.*)?		u:object_r:anr_data_file:s0
 /data/app(/.*)?                       u:object_r:apk_data_file:s0
 /data/app/vmdl.*\.tmp(/.*)?           u:object_r:apk_tmp_file:s0