Restore BlockingEventLoop class name for runBlocking event loop impl

It is a name people are used to seen then they example the coroutineContext
inside runBlocking. The fact that it is also used for unconfined now
is Ok as it is not directly exposed.

Author: elizarov

core/kotlinx-coroutines-core/src/EventLoop.kt

@@ -83,7 +83,7 @@ internal abstract class EventLoopImplBase: EventLoop(), Delay {
     override fun shutdown() {
         // Clean up thread-local reference here -- this event loop is shutting down
         ThreadLocalEventLoop.resetEventLoop()
-        // We should signal that ThreadEventLoop should not accept any more tasks
+        // We should signal that this event loop should not accept any more tasks
         // and process queued events (that could have been added after last processNextEvent)
         isCompleted = true
         closeQueue()
@@ -311,8 +311,8 @@ internal abstract class EventLoopImplBase: EventLoop(), Delay {
     }
 }
 
-internal class ThreadEventLoop(
+internal class BlockingEventLoop(
     override val thread: Thread
 ) : EventLoopImplBase()
 
-internal actual fun createEventLoop(): EventLoop = ThreadEventLoop(Thread.currentThread())
+internal actual fun createEventLoop(): EventLoop = BlockingEventLoop(Thread.currentThread())