Add missing libc++ includes

Bug: 175635923
Test: m vendor.qti.hardware.display.composer-service
Change-Id: I3ee1409e5073c6ea8da6c200ac8d9f9897d17d8e
diff --git a/composer/hwc_buffer_sync_handler.cpp b/composer/hwc_buffer_sync_handler.cpp
index 8bd07f3..9bddb13 100644
--- a/composer/hwc_buffer_sync_handler.cpp
+++ b/composer/hwc_buffer_sync_handler.cpp
@@ -27,6 +27,7 @@
 * IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
 
+#include <assert.h>
 #include <errno.h>
 #include <sync/sync.h>
 #include <utils/constants.h>