eliminate most sync.Pool use, gives a safer but slightly slower interface

src/util/bytes_mobile.go

@@ -1,21 +0,0 @@
-//+build mobile
-
-package util
-
-import "runtime/debug"
-
-func init() {
-	debug.SetGCPercent(25)
-}
-
-// GetBytes always returns a nil slice on mobile platforms.
-func GetBytes() []byte {
-	return nil
-}
-
-// PutBytes does literally nothing on mobile platforms.
-// This is done rather than keeping a free list of bytes on platforms with memory constraints.
-// It's needed to help keep memory usage low enough to fall under the limits set for e.g. iOS NEPacketTunnelProvider apps.
-func PutBytes(bs []byte) {
-	return
-}

src/util/bytes_other.go

@@ -1,18 +0,0 @@
-//+build !mobile
-
-package util
-
-import "sync"
-
-// This is used to buffer recently used slices of bytes, to prevent allocations in the hot loops.
-var byteStore = sync.Pool{New: func() interface{} { return []byte(nil) }}
-
-// GetBytes returns a 0-length (possibly nil) slice of bytes from a free list, so it may have a larger capacity.
-func GetBytes() []byte {
-	return byteStore.Get().([]byte)[:0]
-}
-
-// PutBytes stores a slice in a free list, where it can potentially be reused to prevent future allocations.
-func PutBytes(bs []byte) {
-	byteStore.Put(bs)
-}