Bump procfs to v0.0.7 (#1538)

Update Prometheus procfs library to the latest release.

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

vendor/github.com/prometheus/procfs/proc_environ.go

@@ -14,22 +14,16 @@
 package procfs
 
 import (
-	"io/ioutil"
-	"os"
 	"strings"
+
+	"github.com/prometheus/procfs/internal/util"
 )
 
 // Environ reads process environments from /proc/<pid>/environ
 func (p Proc) Environ() ([]string, error) {
 	environments := make([]string, 0)
 
-	f, err := os.Open(p.path("environ"))
-	if err != nil {
-		return environments, err
-	}
-	defer f.Close()
-
-	data, err := ioutil.ReadAll(f)
+	data, err := util.ReadFileNoStat(p.path("environ"))
 	if err != nil {
 		return environments, err
 	}