KT-5200 Mark unreachable code in lambdas

#KT-5200 Fixed

compiler/testData/diagnostics/tests/controlFlowAnalysis/deadCode/kt5200DeadCodeInLambdas.kt

@@ -0,0 +1,27 @@
+//KT-5200 Mark unreachable code in lambdas
+
+fun test1(): String {
+    doCall @local {
+        () : String ->
+        throw NullPointerException()
+        <!UNREACHABLE_CODE!>"b3"<!> //unmarked
+    }
+
+    return "OK"
+}
+
+fun test2(nonLocal: String, b: Boolean): String {
+    doCall @local {
+        () : String ->
+        if (b) {
+            return@local "b1"
+        } else {
+            return@local "b2"
+        }
+        <!UNREACHABLE_CODE!>"b3"<!> //unmarked
+    }
+
+    return nonLocal
+}
+
+inline fun doCall(block: ()-> String) = block()

compiler/testData/diagnostics/tests/regressions/kt411.kt

@@ -37,7 +37,7 @@ fun t3() : String {
         else {
             <!RETURN_NOT_ALLOWED!>return <!CONSTANT_EXPECTED_TYPE_MISMATCH!>2<!><!>
         }
-        <!RETURN_NOT_ALLOWED_EXPLICIT_RETURN_TYPE_REQUIRED!>return@l 0<!>
+        <!RETURN_NOT_ALLOWED_EXPLICIT_RETURN_TYPE_REQUIRED, UNREACHABLE_CODE!>return@l 0<!>
     }
     )
     invoker(