fix golint issues in core/syncx (#526)

core/syncx/spinlock.go

@@ -5,20 +5,24 @@ import (
 	"sync/atomic"
 )
 
+// A SpinLock is used as a lock a fast execution.
 type SpinLock struct {
 	lock uint32
 }
 
+// Lock locks the SpinLock.
 func (sl *SpinLock) Lock() {
 	for !sl.TryLock() {
 		runtime.Gosched()
 	}
 }
 
+// TryLock tries to lock the SpinLock.
 func (sl *SpinLock) TryLock() bool {
 	return atomic.CompareAndSwapUint32(&sl.lock, 0, 1)
 }
 
+// Unlock unlocks the SpinLock.
 func (sl *SpinLock) Unlock() {
 	atomic.StoreUint32(&sl.lock, 0)
 }