www/minio: Unbreak on i386

vendor/github.com/minio/mc/pkg/disk/stat_freebsd.go:38:41: cannot use st.Atimespec.Sec (variable of type int32) as type int64 in argument to strconv.FormatInt
vendor/github.com/minio/mc/pkg/disk/stat_freebsd.go:38:89: cannot use st.Atimespec.Nsec (variable of type int32) as type int64 in argument to strconv.FormatInt
vendor/github.com/minio/mc/pkg/disk/stat_freebsd.go:51:41: cannot use st.Mtimespec.Sec (variable of type int32) as type int64 in argument to strconv.FormatInt
vendor/github.com/minio/mc/pkg/disk/stat_freebsd.go:51:89: cannot use st.Mtimespec.Nsec (variable of type int32) as type int64 in argument to strconv.FormatInt

Convert syscall.Timespec fields to int64 on all archs.

Reported by: fallout
Approved by: portmgr (blanket, build fix)