unused variables warnings (#547) #353

Job	Run time
windows-msvc-shared (AVRO)	7m 6s
windows-msvc-shared (CAPNPROTO)	7m 58s
windows-msvc-shared (CBOR)	8m 22s
windows-msvc-shared (FLEXBUFFERS)	5m 41s
windows-msvc-shared (TOML)	5m 16s
windows-msvc-shared (UBJSON)	7m 4s
windows-msvc-shared (JSON)	10m 41s
windows-msvc-shared (XML)	3m 55s
windows-msvc-shared (YAML)	4m 16s
windows-msvc-shared (PARQUET)	40m 38s
windows-msvc-shared (MSGPACK)	4m 30s
windows-msvc (JSON)	10m 0s
windows-msvc (benchmarks)	47m 40s
windows-msvc (UBJSON)	6m 56s
windows-msvc (CAPNPROTO)	7m 48s
windows-msvc (YAML)	4m 7s
windows-msvc (XML)	3m 44s
windows-msvc (AVRO)	7m 21s
windows-msvc (CBOR)	8m 56s
windows-msvc (MSGPACK)	3m 57s
windows-msvc (FLEXBUFFERS)	5m 18s
windows-msvc (PARQUET)	38m 39s
windows-msvc (TOML)	3m 39s
	4h 13m 32s

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