Fix libmedia includes.

Test: works with BOARD_VNDK_VERSION := current
Bug: 33241851
Change-Id: Idb6319563dfe83807d32ee54eb2fe66346c9f54a
diff --git a/media/libmedia/Android.mk b/media/libmedia/Android.mk
index b0bd22e..e2d48a2 100644
--- a/media/libmedia/Android.mk
+++ b/media/libmedia/Android.mk
@@ -86,6 +86,8 @@
         android.hardware.media.omx@1.0 \
         android.hidl.memory@1.0 \
 
+LOCAL_HEADER_LIBRARIES := libmedia_headers
+
 # for memory heap analysis
 LOCAL_STATIC_LIBRARIES := libc_malloc_debug_backtrace libc_logging