Avoid recursive runtime init bug. (#3020)

backend.native/tests/build.gradle

@@ -598,6 +598,12 @@ task array_to_any(type: RunKonanTest) {
     source = "codegen/basics/array_to_any.kt"
 }
 
+task runtime_basic_init(type: RunStandaloneKonanTest) {
+    source = "runtime/basic/init.kt"
+    flags = ['-g']
+    expectedExitStatus = 0
+}
+
 task runtime_basic_exit(type: RunStandaloneKonanTest) {
     source = "runtime/basic/exit.kt"
     expectedExitStatus = 42

backend.native/tests/runtime/basic/init.kt

@@ -0,0 +1,4 @@
+val x = initRuntimeIfNeeded()
+
+fun main() {
+}

runtime/src/main/cpp/Runtime.cpp

@@ -79,13 +79,14 @@ RuntimeState* initRuntime() {
   SetKonanTerminateHandler();
   RuntimeState* result = konanConstructInstance<RuntimeState>();
   if (!result) return nullptr;
+  RuntimeCheck(runtimeState == nullptr, "No active runtimes allowed");
+  runtimeState = result;
   result->memoryState = InitMemory();
   bool firstRuntime = atomicAdd(&aliveRuntimesCount, 1) == 1;
   // Keep global variables in state as well.
   if (firstRuntime) {
     isMainThread = 1;
     konan::consoleInit();
-
     InitOrDeinitGlobalVariables(INIT_GLOBALS);
   }
   InitOrDeinitGlobalVariables(INIT_THREAD_LOCAL_GLOBALS);
@@ -117,7 +118,7 @@ void AppendToInitializersTail(InitNode *next) {
 
 void Kotlin_initRuntimeIfNeeded() {
   if (runtimeState == nullptr) {
-    runtimeState = initRuntime();
+    initRuntime();
     RuntimeCheck(updateStatusIf(runtimeState, SUSPENDED, RUNNING), "Cannot transition state to RUNNING for init");
     // Register runtime deinit function at thread cleanup.
     konan::onThreadExit(Kotlin_deinitRuntimeIfNeeded);