Make module be able to be built as dymanic

[msva]

(reworked patch from FRiCKLE/ngx_postgres#54)

[msva]

🦗

[zhuizhuhaomeng]

Thanks for your contribution.
Would you add a .travis.yml for the CI in another PR first ?

[msva]

well, I can try (although I doubt that I'll have time for that until next weekend).
Althought, I've few pre-questions:

1. is it any template anywhere?
   or

2. is it any info about what should be run during CI? Just only nginx tests?

3. is travis mandatory? Isn't it may be better to use github workflows instead?

[zhuizhuhaomeng]

Here is an example.
https://github.com/openresty/lua-redis-parser/blob/master/.travis.yml