* simplify Makefile in CGO

* remove gcc -M option

* extract decNumber Makefile

* init support union in parser

* add more ut

* add except in parser(have conflicts)


Co-authored-by: aubin <1030420200@qq.com>

* Replace ring with agg

* Fix the bug of bit_and

* Modify the behavior of bit_and in bvt to be consistent with mysql

* Rewrite decimal function macro.

* Move int/uint/float add to cgo.  Benchmarked.

For 8K int/uint/float operations, go perf is roughly 10us.   Cgo
is roughly 2us.

For 8K dec64/dec128, right now it is 100 - 200 us. This may argue
for our own implementation of decimal.

Co-authored-by: nnsgmsone <nnsmgsone@outlook.com>

Plus first.  If it looks ok, I will work out the rest.

* add coalesceString

* change if/case type check

* retag some case to 3333

* fix cast datetime to string bug

* change bvt result

* little performance optimization