* [TD-4001]<fix>: taosdemo restful segfault.

due to gethostbyname() is not thread-safe.

* fix uninitialized variable when invalid mode.
Co-authored-by: NShuduo Sang <sdsang@taosdata.com>

[TD-3984]union issues

[TD-3996]udc query issue

* [TD-3985]<fix>: taosdemo timestamp step overflow.

* fix specified subscribe test.

* replace potential overflow of int32 to int64

* replace potential int32 overflow variables to int64.

* replace potential int32 overflow variables to int64.

* change max of int16 to int64 after type changed.
Co-authored-by: NShuduo Sang <sdsang@taosdata.com>

[TD-2039] <test> verify the bug of TD-2039

[TD-3988]add mac test on Appveyor

TD-3948: specify insertion columns after supertable tags

* [TD-3985]<fix>: taosdemo timestamp step overflow.

* fix specified subscribe test.

* replace potential overflow of int32 to int64

* replace potential int32 overflow variables to int64.

* replace potential int32 overflow variables to int64.
Co-authored-by: NShuduo Sang <sdsang@taosdata.com>

[TD-3991]fix client log

* [TD-3985]<fix>: taosdemo timestamp step overflow.

* fix specified subscribe test.
Co-authored-by: NShuduo Sang <sdsang@taosdata.com>

The update contains TD-3983 TD-3912 fixes.

[TD-3921] <test> add case to resolv show streams return erro msg

[TD-3920] <test> add case to fix the bug of TD-3920

[td-3951]<fix>: check the input value of big int which is overflowed.

Co-authored-by: NShuduo Sang <sdsang@taosdata.com>

[TD-3940]CQ crash when vnode changes

Co-authored-by: NShuduo Sang <sdsang@taosdata.com>