Add Lyng deferred cancellation support

lynglib/src/commonTest/kotlin/CoroutinesTest.kt

@@ -58,6 +58,30 @@ class TestCoroutines {
         )
     }
 
+    @Test
+    fun testDeferredCancel() = runTest {
+        eval(
+            """
+            var reached = false
+            val d = launch {
+                delay(100)
+                reached = true
+                "ok"
+            }
+
+            d.cancel()
+            d.cancel()
+            assertThrows(CancellationException) { d.await() }
+
+            delay(150)
+
+            assert(d.isCancelled)
+            assert(!d.isActive)
+            assert(!reached)
+        """.trimIndent()
+        )
+    }
+
     @Test
     fun testMutex() = runTest {
         eval(