aarch64 的CentOS Linux release 7.6.1810 (AltArch),brpc1.5.0 echo_test 退出报错sched_to itself!double free or corruption

**Describe the bug**
**1、启动echo_server ,啥都不做**
sudo ./echo_server --port=8341
I0226 18:12:36.422261 64782 src/brpc/server.cpp:1113] Server[EchoServiceImpl] is serving on port=8341.
I0226 18:12:36.422582 64782 src/brpc/server.cpp:1116] Check out http://tjyxy01-ks3-dev144059169.tjyxy01.ksyun.com:8341 in web browser.
EchoServer started at 0.0.0.0:8341
**2、ctrl+c退出即报错**
I0226 18:12:37.075939 64782 src/brpc/server.cpp:1173] Server[EchoServiceImpl] is going to quit
F0226 18:12:37.076134 64821 src/bthread/task_group.cpp:629] bthread=4294975488 sched_to itself!
*** Error in `./echo_server': double free or corruption (!prev): 0x0000ffff1401c780 ***
======= Backtrace: =========
/lib64/libc.so.6(+0x7d1ec)[0xffffb47fd1ec]
/lib64/libstdc++.so.6(_ZNSs7reserveEm+0xb0)[0xffffb4acda74]
./echo_server[0x57a5a0]
./echo_server[0x4ab4e8]

**To Reproduce**

**Expected behavior**
正常退出不要报错

**Versions**
OS:CentOS Linux release 7.6.1810 (AltArch),
Compiler:
brpc:1.5.0
protobuf:2.5.0

**Additional context/screenshots**

Reproduce the failure with echo_server on CentOS Linux 7.6.1810 (AltArch), brpc 1.5.0, and protobuf 2.5.0, then inspect src/bthread/task_group.cpp around line 629 and the shutdown path reported by the log. Done means stopping the server with Ctrl+C exits cleanly without “sched_to itself!” or double-free errors.

Written by the indexing model from the issue text.