block/snapshot: Fix compiler warning with -Wshadow=local

No need to declare a new variable in the the inner code block
here, we can re-use the "ret" variable that has been declared
at the beginning of the function. With this change, the code
can now be successfully compiled with -Wshadow=local again.

Signed-off-by: Thomas Huth <thuth@redhat.com>
Message-ID: <20231023175038.111607-1-thuth@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
[Commit message tweaked]
Signed-off-by: Markus Armbruster <armbru@redhat.com>

block/snapshot.c

@@ -629,17 +629,15 @@ int bdrv_all_goto_snapshot(const char *name,
     while (iterbdrvs) {
         BlockDriverState *bs = iterbdrvs->data;
         AioContext *ctx = bdrv_get_aio_context(bs);
-        int ret = 0;
         bool all_snapshots_includes_bs;
 
         aio_context_acquire(ctx);
         bdrv_graph_rdlock_main_loop();
         all_snapshots_includes_bs = bdrv_all_snapshots_includes_bs(bs);
         bdrv_graph_rdunlock_main_loop();
 
-        if (devices || all_snapshots_includes_bs) {
-            ret = bdrv_snapshot_goto(bs, name, errp);
-        }
+        ret = (devices || all_snapshots_includes_bs) ?
+              bdrv_snapshot_goto(bs, name, errp) : 0;
         aio_context_release(ctx);
         if (ret < 0) {
             bdrv_graph_rdlock_main_loop();