Main thread spread exception when thread-mgr is enabled (#1889)

And refactor clear_wasi_proc_exit_exception, refer to
https://github.com/bytecodealliance/wasm-micro-runtime/pull/1869

samples/multi-thread/wasm-apps/CMakeLists.txt

@@ -38,3 +38,6 @@ set (CMAKE_EXE_LINKER_FLAGS
 
 add_executable(test.wasm  main.c)
 target_link_libraries(test.wasm)
+
+add_executable(main_thread_exception.wasm  main_thread_exception.c)
+target_link_libraries(main_thread_exception.wasm)

samples/multi-thread/wasm-apps/main_thread_exception.c

@@ -0,0 +1,36 @@
+/*
+ * Copyright (C) 2019 Intel Corporation.  All rights reserved.
+ * SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+ */
+
+#include <stdio.h>
+#include <pthread.h>
+
+typedef struct ThreadArgs {
+    int start;
+    int length;
+} ThreadArgs;
+
+void *
+thread(void *args)
+{
+    while (1) {
+        /* When other threads (including main thread) throw exception,
+            this thread can successfully exit the dead loop */
+    }
+}
+
+int
+main()
+{
+    pthread_t tids;
+
+    if (pthread_create(&tids, NULL, thread, NULL) != 0) {
+        printf("pthread_create failed\n");
+    }
+
+    /* Trigger an exception */
+    __builtin_trap();
+
+    return 0;
+}