btrfs plugin needs CGO support. However on riscv64, cgo is only support on go1.16 (not released yet). Instead of setting no_btrfs manually, adding a cgo tag tells the compiler to skip it automatically. Signed-off-by: Shengjing Zhu <zhsj@debian.org>
Part of #4514 Signed-off-by: Jian Zeng <anonymousknight96@gmail.com>