net: remove the dregs of old built-in poll server

We don't need placeholders for the old built-in poll server any more.

Change-Id: I3a510aec6a30bc2ac97676c400177cdfe557b8dc
Reviewed-on: https://go-review.googlesource.com/3863Reviewed-by: Dmitry Vyukov <dvyukov@google.com>

src/net/fd_poll_nacl.go

@@ -18,18 +18,11 @@ func (pd *pollDesc) Init(fd *netFD) error { pd.fd = fd; return nil }
 
 func (pd *pollDesc) Close() {}
 
-func (pd *pollDesc) Lock() {}
-
-func (pd *pollDesc) Unlock() {}
-
-func (pd *pollDesc) Wakeup() {}
-
-func (pd *pollDesc) Evict() bool {
+func (pd *pollDesc) Evict() {
 	pd.closing = true
 	if pd.fd != nil {
 		syscall.StopIO(pd.fd.sysfd)
 	}
-	return false
 }
 
 func (pd *pollDesc) Prepare(mode int) error {

src/net/fd_poll_runtime.go

@@ -48,23 +48,12 @@ func (pd *pollDesc) Close() {
 	pd.runtimeCtx = 0
 }
 
-func (pd *pollDesc) Lock() {
-}
-
-func (pd *pollDesc) Unlock() {
-}
-
-func (pd *pollDesc) Wakeup() {
-}
-
 // Evict evicts fd from the pending list, unblocking any I/O running on fd.
-// Return value is whether the pollServer should be woken up.
-func (pd *pollDesc) Evict() bool {
+func (pd *pollDesc) Evict() {
 	if pd.runtimeCtx == 0 {
-		return false
+		return
 	}
 	runtime_pollUnblock(pd.runtimeCtx)
-	return false
 }
 
 func (pd *pollDesc) Prepare(mode int) error {

src/net/fd_unix.go

@@ -187,9 +187,7 @@ func (fd *netFD) writeUnlock() {
 }
 
 func (fd *netFD) Close() error {
-	fd.pd.Lock() // needed for both fd.incref(true) and pollDesc.Evict
 	if !fd.fdmu.IncrefAndClose() {
-		fd.pd.Unlock()
 		return errClosing
 	}
 	// Unblock any I/O.  Once it all unblocks and returns,
@@ -197,12 +195,8 @@ func (fd *netFD) Close() error {
 	// the final decref will close fd.sysfd.  This should happen
 	// fairly quickly, since all the I/O is non-blocking, and any
 	// attempts to block in the pollDesc will return errClosing.
-	doWakeup := fd.pd.Evict()
-	fd.pd.Unlock()
+	fd.pd.Evict()
 	fd.decref()
-	if doWakeup {
-		fd.pd.Wakeup()
-	}
 	return nil
 }