use pointer to byte slices in the buffer pool

https://staticcheck.io/docs/staticcheck#SA6002 suggests to use pointers
to objects in the sync.Pool.

buffer_pool_test.go

@@ -8,25 +8,14 @@ import (
 )
 
 var _ = Describe("Buffer Pool", func() {
-	It("returns buffers of correct len and cap", func() {
-		buf := getPacketBuffer()
-		Expect(buf).To(HaveLen(0))
+	It("returns buffers of cap", func() {
+		buf := *getPacketBuffer()
 		Expect(buf).To(HaveCap(int(protocol.MaxReceivePacketSize)))
 	})
 
-	It("zeroes put buffers' length", func() {
-		for i := 0; i < 1000; i++ {
-			buf := getPacketBuffer()
-			putPacketBuffer(buf[0:10])
-			buf = getPacketBuffer()
-			Expect(buf).To(HaveLen(0))
-			Expect(buf).To(HaveCap(int(protocol.MaxReceivePacketSize)))
-		}
-	})
-
 	It("panics if wrong-sized buffers are passed", func() {
 		Expect(func() {
-			putPacketBuffer([]byte{0})
+			putPacketBuffer(&[]byte{0})
 		}).To(Panic())
 	})
 })