miext/sync: Fix needless ABI change

The initialized field was added in:

    commit 82f01ad786
    Author: Alex Goins <agoins@nvidia.com>
    Date:   Wed Apr 10 13:48:02 2019 -0500

        xsync: Add resource inside of SyncCreate, export SyncCreate

But it added this field not at the end of SyncObject. It may not have
been _usefully_ possible to create those from another extension prior to
that commit, but that's still an ABI-incompatible change.

miext/sync/misyncstr.h

@@ -43,8 +43,8 @@ struct _SyncObject {
     struct _SyncTriggerList *pTriglist; /* list of triggers */
     XID id;                     /* resource ID */
     unsigned char type;         /* SYNC_* */
-    Bool initialized;           /* FALSE if created but not initialized */
     Bool beingDestroyed;        /* in process of going away */
+    Bool initialized;           /* FALSE if created but not initialized */
 };
 
 typedef struct _SyncCounter {