add event-driven framework

see examples/event_driven_at_module and examples/event_driven_hello_world, demo project: TencentOS-tiny\board\TencentOS_tiny_EVB_MX\KEIL\event_driven_hello_world

kernel/evtdrv/tos_evtdrv_task.c

@@ -0,0 +1,30 @@
+#include "tos_evtdrv.h"
+
+#if TOS_CFG_EVENT_DRIVEN_EN > 0u
+
+__API__ evtdrv_task_id_t tos_evtdrv_task_self(void)
+{
+    return evtdrv_curr_task;
+}
+
+__KERNEL__ evtdrv_bool_t evtdrv_task_id_is_invalid(evtdrv_task_id_t task_id)
+{
+    return task_id >= evtdrv_task_table_size;
+}
+
+__KERNEL__ evtdrv_bool_t evtdrv_task_is_self(evtdrv_task_id_t task_id)
+{
+    return task_id == evtdrv_curr_task;
+}
+
+__KERNEL__ void evtdrv_task_init(void)
+{
+    evtdrv_task_id_t i;
+
+    for (i = 0; i < evtdrv_task_table_size; ++i) {
+        (evtdrv_task_table[i])(TOS_EVTDRV_SYS_EVENT_INIT);
+    }
+}
+
+#endif
+