Fix unused warning for `IsFdOpen()`
Fix unused warning for `IsFdOpen()`

PiperOrigin-RevId: 282346983
Change-Id: I7010caf0e6f3ddb420ef992f6aa2554d540667a3

google/sandboxed-api,google/sandboxed-api,google/sandboxed-api,google/sandboxed-api