thread-mgr: Fix spread "wasi proc exit" exception and atomic.wait issues (#1988)

Raising "wasi proc exit" exception, spreading it to other threads and then
clearing it in all threads may result in unexpected behavior: the sub thread
may end first, handle the "wasi proc exit" exception and clear exceptions
of other threads, including the main thread. And when main thread's
exception is cleared, it may continue to run and throw "unreachable"
exception. This also leads to some assertion failed.

Ignore exception spreading for "wasi proc exit" and don't clear exception
of other threads to resolve the issue.

And add suspend flag check after atomic wait since the atomic wait may
be notified by other thread when exception occurs.

core/iwasm/common/wasm_runtime_common.c

@@ -1880,8 +1880,10 @@ clear_wasi_proc_exit_exception(WASMModuleInstanceCommon *module_inst_comm)
     if (exception && !strcmp(exception, "Exception: wasi proc exit")) {
         /* The "wasi proc exit" exception is thrown by native lib to
            let wasm app exit, which is a normal behavior, we clear
-           the exception here. */
-        wasm_set_exception(module_inst, NULL);
+           the exception here. And just clear the exception of current
+           thread, don't call `wasm_set_exception(module_inst, NULL)`
+           which will clear the exception of all threads. */
+        module_inst->cur_exception[0] = '\0';
         return true;
     }
     return false;