The spawn proxy thread is a special existence in NuttX, usually some developers spend a lot of time on stack overflow of spawn proxy thread: https://github.com/apache/nuttx/issues/9046 https://github.com/apache/nuttx/pull/9081 In order to avoid similar issues, this PR will remove spawn proxy thread to simplify the process of task/posix_spawn(). 1. Postpone the related processing of spawn file actions until after task_init() 2. Delete the temporary thread of spawn proxy and related global variables Signed-off-by: chao an <anchao@xiaomi.com>