Mark libstagefright/flac as being a mainline directory.

Bug: 182386024
Test: repo upload
Change-Id: Ic93dc4705a513ecfc179eb69dde5d28f2139a08a
diff --git a/MainlineFiles.cfg b/MainlineFiles.cfg
index f694a41..490bbbf 100644
--- a/MainlineFiles.cfg
+++ b/MainlineFiles.cfg
@@ -1,10 +1,13 @@
-# 
+#
 # mainline files for frameworks/av
+# this list used by tools/mainline_hook_*.sh to help separate
+# mainline changes vs framework changes, which release at different paces.
+#
 #
 # ignore comment (#) lines and blank lines
 # rest are path prefixes starting at root of the project
 # (so OWNERS, not frameworks/av/OWNERS)
-# 
+#
 # path
 # INCLUDE path
 # EXCLUDE path
@@ -24,4 +27,5 @@
 media/codec2/components/
 media/codecs/
 media/extractors/
-media/libstagefright/mpeg2ts
+media/libstagefright/mpeg2ts/
+media/libstagefright/flac/