add an offset field to gralloc handles so the framebuffer can work with copybit
diff --git a/modules/gralloc/gralloc.cpp b/modules/gralloc/gralloc.cpp
index 5a38b33..6ec65e9 100644
--- a/modules/gralloc/gralloc.cpp
+++ b/modules/gralloc/gralloc.cpp
@@ -147,6 +147,7 @@
     }
     
     hnd->base = vaddr;
+    hnd->offset = vaddr - intptr_t(m->framebuffer->base);
     *pHandle = hnd;
 
     return 0;