Update filesystem freebsd

Upstream x/sys/unix changed types.

Signed-off-by: Ben Kochie <superq@gmail.com>

Author: SuperQ

collector/filesystem_freebsd.go

@@ -16,9 +16,6 @@
 package collector
 
 import (
-	"bytes"
-	"unsafe"
-
 	"github.com/go-kit/kit/log/level"
 	"golang.org/x/sys/unix"
 )
@@ -30,15 +27,6 @@ const (
 	noWait                = 0x2 // MNT_NOWAIT
 )
 
-func gostring(b []int8) string {
-	bb := *(*[]byte)(unsafe.Pointer(&b))
-	idx := bytes.IndexByte(bb, 0)
-	if idx < 0 {
-		return ""
-	}
-	return string(bb[:idx])
-}
-
 // Expose filesystem fullness.
 func (c *filesystemCollector) GetStats() ([]filesystemStats, error) {
 	n, err := unix.Getfsstat(nil, noWait)
@@ -52,14 +40,14 @@ func (c *filesystemCollector) GetStats() ([]filesystemStats, error) {
 	}
 	stats := []filesystemStats{}
 	for _, fs := range buf {
-		mountpoint := gostring(fs.Mntonname[:])
+		mountpoint := string(fs.Mntonname[:])
 		if c.ignoredMountPointsPattern.MatchString(mountpoint) {
 			level.Debug(c.logger).Log("msg", "Ignoring mount point", "mountpoint", mountpoint)
 			continue
 		}
 
-		device := gostring(fs.Mntfromname[:])
-		fstype := gostring(fs.Fstypename[:])
+		device := string(fs.Mntfromname[:])
+		fstype := string(fs.Fstypename[:])
 		if c.ignoredFSTypesPattern.MatchString(fstype) {
 			level.Debug(c.logger).Log("msg", "Ignoring fs type", "type", fstype)
 			continue