hwc: sync-point implementation.

Add sync pt implementation.
Add genlock and sync pt under conditional compilation flags.

Change-Id: I32fb7f6051ccc706662152e90ac15b6b6743f897
Signed-off-by: Iliyan Malchev <malchev@google.com>
diff --git a/libhwcomposer/hwc_utils.h b/libhwcomposer/hwc_utils.h
index 184d967..1153cc7 100644
--- a/libhwcomposer/hwc_utils.h
+++ b/libhwcomposer/hwc_utils.h
@@ -87,6 +87,9 @@
 // Waits for the fb_post to finish PAN (primary commit)
 void wait4Pan(hwc_context_t* ctx);
 
+//Sync point impl.
+int hwc_sync(hwc_display_contents_1_t* list);
+
 // Inline utility functions
 static inline bool isSkipLayer(const hwc_layer_1_t* l) {
     return (UNLIKELY(l && (l->flags & HWC_SKIP_LAYER)));