Fix "constant 2435016766 overflows int32" on GOARCH=arm
Fix "constant 2435016766 overflows int32" on GOARCH=arm

Fix #1

Signed-off-by: Akihiro Suda <10ddef0dea2a66ab193b07198faa879adcb213d8@hco.ntt.co.jp>

dennwc/btrfs