binder_parcel_fuzzer: close FDs in unflatten

Even if we don't want to use them, we need to take ownership and close
them to avoid leaking.

Ignore-AOSP-First: na
Flag: TEST_ONLY
Test: binder_parcel_fuzzer
Bug: 406499223
Change-Id: I01f5f1d5da49067116eaee72af64ac08a3f05413

Author: devinmoore-goog

libs/binder/tests/parcel_fuzzer/binder.cpp

@@ -62,13 +62,17 @@ struct ExampleFlattenable : public android::Flattenable<ExampleFlattenable> {
         FUZZ_LOG() << "should not reach";
         abort();
     }
-    status_t unflatten(void const*& buffer, size_t& size, int const*& /*fds*/, size_t& /*count*/) {
+    status_t unflatten(void const*& buffer, size_t& size, int const*& fds, size_t& count) {
+        for (size_t i = 0; i < count; i++) {
+            close(fds[i]);
+        }
         if (size < sizeof(mValue)) {
             return android::NO_MEMORY;
         }
         android::FlattenableUtils::read(buffer, size, mValue);
         return android::OK;
     }
+
 private:
     int32_t mValue = 0xFEEDBEEF;
 };