x/ref: Switch v23_syncbase_Handle from void* to uintptr_t

The 'void*' for v23_syncbase_Handle is causing random crashes because
Go does some checks that the value points to some valid memory
address.

MultiPart: 1/2
Change-Id: I916af0ddbca8443ed709aaa26aaf792946b52d07
diff --git a/services/syncbase/bridge/cgo/lib.h b/services/syncbase/bridge/cgo/lib.h
index d1ad5e0..505d180 100644
--- a/services/syncbase/bridge/cgo/lib.h
+++ b/services/syncbase/bridge/cgo/lib.h
@@ -153,7 +153,7 @@
 ////////////////////////////////////////
 // Functions
 
-typedef void* v23_syncbase_Handle;
+typedef uintptr_t v23_syncbase_Handle;
 
 typedef struct {
   v23_syncbase_Handle handle;