Remove padding in packetcache.

Since the packet entries are already overdimensioned, there's no
need to add additional padding.

packetcache/packetcache.go

@@ -10,7 +10,6 @@ type entry struct {
 	seqno  uint16
 	length uint16
 	buf    [BufSize]byte
-	pad    [32 - (BufSize+4)%32]byte // avoid false sharing
 }
 
 type Cache struct {

packetcache/packetcache_test.go

@@ -5,7 +5,6 @@ import (
 	"math/rand"
 	"sync"
 	"testing"
-	"unsafe"
 
 	"github.com/pion/rtcp"
 )
@@ -82,16 +81,6 @@ func TestCacheOverflow(t *testing.T) {
 	}
 }
 
-func TestCacheAlignment(t *testing.T) {
-	cache := New(16)
-	for i := range cache.entries {
-		p := unsafe.Pointer(&cache.entries[i])
-		if uintptr(p)%32 != 0 {
-			t.Errorf("%v: alignment %v", i, uintptr(p)%32)
-		}
-	}
-}
-
 func TestBitmap(t *testing.T) {
 	value := uint64(0xcdd58f1e035379c0)
 	packet := make([]byte, 1)