GPU (macOS): fix build error in MacOS 10.13 (#1556)

* Fix build error in MacOS 10.13

* Update gpu_apple.m

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Co-authored-by: Carter Li <CarterLi@users.noreply.github.com>

src/detection/gpu/gpu_apple.m

@@ -67,10 +67,10 @@ const char* ffGpuDetectMetal(FFlist* gpus)
 
             gpu->type = device.location == MTLDeviceLocationBuiltIn ? FF_GPU_TYPE_INTEGRATED : FF_GPU_TYPE_DISCRETE;
             gpu->index = (uint32_t) device.locationNumber;
-            #endif
 
             if (device.hasUnifiedMemory && device.recommendedMaxWorkingSetSize > 0)
                 gpu->shared.total = device.recommendedMaxWorkingSetSize;
+            #endif
         }
         return NULL;
     }