[wip] c/neco: init and demo

[kindy]

https://github.com/tidwall/neco

[kindy]

@xushiwei thanks for the review, I'll fix it latter.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 97.71%. Comparing base (6e02dac) to head (c0d7ff9).
Report is 21 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #525   +/-   ##
=======================================
  Coverage   97.71%   97.71%           
=======================================
  Files          19       19           
  Lines        4511     4514    +3     
=======================================
+ Hits         4408     4411    +3     
  Misses         87       87           
  Partials       16       16           

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[xushiwei]

https://github.com/goplus/llgo/blob/main/c/neco/neco.go#L54

change

type Coro = func(argc c.Int, __llgo_va_list ...any)

to:

type Coro = func(argc c.Int, argv *c.Pointer)