Update for cleanups in hwc interface

Also store the hwc_procs_t* into a dedicated field instead of one of
the hwc_composer_device_1_t::reserved_procs slots, which are supposed
to be NULL so the structure can be extended without breaking backwards
binary compatibility.

Change-Id: I11e6bc713958d854aba418242caa749cbcb21f1d
diff --git a/libhwcomposer/hwc_utils.h b/libhwcomposer/hwc_utils.h
index 84309ac..b586fa8 100644
--- a/libhwcomposer/hwc_utils.h
+++ b/libhwcomposer/hwc_utils.h
@@ -124,6 +124,7 @@
 // This structure contains overall state
 struct hwc_context_t {
     hwc_composer_device_1_t device;
+    const hwc_procs_t* proc;
     int numHwLayers;
     int overlayInUse;
     hwc_display_t dpys[MAX_NUM_DISPLAYS];