Release v0.10.0 does not build with GOOS=windows + GOARCH=amd64

Packages importing v0.10.0 of this module (github.com/prometheus/procfs) cannot build for amd64 windows.

Issue likely introduced via 80824fa and solved for certain operating systems via #523 (but not windows!)

Example

10:41 $ GOOS=windows GOARCH=amd64 go build .
# github.com/prometheus/procfs
../../../../pkg/mod/github.com/prometheus/procfs@v0.10.0/fs_statfs_type.go:25:18: undefined: syscall.Statfs_t
../../../../pkg/mod/github.com/prometheus/procfs@v0.10.0/fs_statfs_type.go:26:17: undefined: syscall.Statfs

Release v0.10.0 is a breaking change. Kindly look into this.