AHAL: enable audio hal for linux platform

Change-Id: I7de481eb7b04985f232dfe833d76e80907081bdb
Signed-off-by: Hexuan Zhu <hexuzhu@codeaurora.org>
diff --git a/Makefile.am b/Makefile.am
old mode 100644
new mode 100755
index d4aef58..38e98ea
--- a/Makefile.am
+++ b/Makefile.am
@@ -1,4 +1,4 @@
-SUBDIRS = hal post_proc
+SUBDIRS = hal hal/audio_extn
 
 if QAHW_SUPPORT
 SUBDIRS += qahw_api qahw_api/test