Fix VNDK Compilation Errors

VNDK restrictions doesn't includes standard headers by
default, add them explicitly.

Change-Id: Icafac6f07fcdf58fccaabde8d472509090fb3e6f
diff --git a/post_proc/asphere.c b/post_proc/asphere.c
index 3ec2818..20ca694 100644
--- a/post_proc/asphere.c
+++ b/post_proc/asphere.c
@@ -40,6 +40,7 @@
 #include <cutils/str_parms.h>
 #include <cutils/properties.h>
 #include <hardware/audio_effect.h>
+#include <pthread.h>
 #include "bundle.h"
 #include "equalizer.h"
 #include "bass_boost.h"