miext/sync: Make struct _SyncObject::initialized fully ABI compatible

With a 32-bit build, putting the initialized field at the end of the
struct bumped the struct size from 20 bytes to 24, changing the layout
of other structs embedding struct _SyncObject. While this would be
acceptable on master, it caused crashes with 1.20.

Making the initialized field a char and putting it in the hole before
the beingDestroyed field restores the 32-bit ABI as well.

Fixes https://gitlab.freedesktop.org/xorg/xserver/issues/892

Reviewed-by: Aaron Plattner <[email protected]>
Reviewed-by: Alex Goins <[email protected]>
(cherry picked from commit 0d8cc7bb180468fee72330f40d87f6e9db7b42c0)

Author: Michel Dänzer

miext/sync/misyncstr.h

@@ -43,8 +43,8 @@ struct _SyncObject {
     struct _SyncTriggerList *pTriglist; /* list of triggers */
     XID id;                     /* resource ID */
     unsigned char type;         /* SYNC_* */
+    unsigned char 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 {