vendor: update buildkit to v0.8

Signed-off-by: Tonis Tiigi <tonistiigi@gmail.com>

vendor/github.com/sirupsen/logrus/entry.go

@@ -13,7 +13,6 @@ import (
 )
 
 var (
-	bufferPool *sync.Pool
 
 	// qualified package name, cached at first use
 	logrusPackage string
@@ -31,12 +30,6 @@ const (
 )
 
 func init() {
-	bufferPool = &sync.Pool{
-		New: func() interface{} {
-			return new(bytes.Buffer)
-		},
-	}
-
 	// start at the bottom of the stack before the package-name cache is primed
 	minimumCallerDepth = 1
 }
@@ -243,9 +236,12 @@ func (entry Entry) log(level Level, msg string) {
 
 	entry.fireHooks()
 
-	buffer = bufferPool.Get().(*bytes.Buffer)
+	buffer = getBuffer()
+	defer func() {
+		entry.Buffer = nil
+		putBuffer(buffer)
+	}()
 	buffer.Reset()
-	defer bufferPool.Put(buffer)
 	entry.Buffer = buffer
 
 	entry.write()