Add missing c_stdlib_version in Windows variant

[jakirkham]

Recently as part of the {{ stdlib("c") }} work ( conda-forge/conda-forge.github.io#2102 ), c_stdlib_version was added to Windows variants. However this feedstock is currently not updated to have that. So we should add it (by re-rendering)

[jakirkham]

@conda-forge-admin , please re-render

[conda-forge-webservices]

Hi! This is the friendly automated conda-forge-webservice.

I just wanted to let you know that I started rerendering the recipe in #20.