Merge pull request #728 from fancybits/android-filesystems

ignore /proc/filesystems errors on android

disk/disk_linux.go

@@ -10,6 +10,7 @@ import (
 	"io/ioutil"
 	"os"
 	"path/filepath"
+	"runtime"
 	"strconv"
 	"strings"
 
@@ -244,7 +245,7 @@ func PartitionsWithContext(ctx context.Context, all bool) ([]PartitionStat, erro
 	}
 
 	fs, err := getFileSystems()
-	if err != nil {
+	if err != nil && all {
 		return nil, err
 	}