[PATCH] meson: update doc logic for Windows

[Thomas Monjalon]

Hello,

Thank you for looking at this problem.

26/03/2022 03:59, Vipin Varghese:
> Support for shell scripts doxy-html-custom, generate_doxygen and
> generate_examples are absent. The current patch address the same by
> disabling document build notifying the user.

It should not prevent generating guides with sphinx.

> Steps to reproduce the error:
>  - Install dependencies doxygen & sphinix build on Windwos server 2019.
>  - Build DPDK with option enable_docs=true for API or User Guide.
> 
> This produces error
> ```
> FAILED: doc/api/examples.dox
> sh -e dpdk/doc/api/generate_examples.sh dpdk/examples doc/api/examples.dox
> ```

I suppose we could replace shell scripts with Python equivalent.