turnip: Close sync_fd only if it is a valid file descriptor.

Fix defects reported by Coverity Scan.

Argument cannot be negative (NEGATIVE_RETURNS)
negative_returns: sync_fd is passed to a parameter that cannot be negative.

Fixes: cec0bc73e55 ("turnip: rework fences to use syncobjs")
Signed-off-by: Vinson Lee <vlee@freedesktop.org>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/7647>
(cherry picked from commit 69cad1f96ef4481cc2395def9c993ddcbb0e2540)
diff --git a/.pick_status.json b/.pick_status.json
index a53dfb0..06eab24 100644
--- a/.pick_status.json
+++ b/.pick_status.json
@@ -463,7 +463,7 @@
         "description": "turnip: Close sync_fd only if it is a valid file descriptor.",
         "nominated": true,
         "nomination_type": 1,
-        "resolution": 0,
+        "resolution": 1,
         "master_sha": null,
         "because_sha": "cec0bc73e550859635a71d330625bccdf71e87ee"
     },