Migrate to Jinja2 compiler syntax

[regro-cf-autotick-bot]

This PR was created by the cf-regro-autotick-bot.

The cf-regro-autotick-bot is a service to automatically track the dependency graph, migrate packages, and propose package version updates for conda-forge. It is very likely that the current package version for this feedstock is out of date or needed migration.

List of changes done to the recipe: Renamed build with host Moving m2-autoconf from host to build Moving m2-automake{{am_version}} from host to build Moving m2-libtool from host to build Removing m2w64-toolchain in favour of compiler() Moving pkg-config from host to build Moving posix from host to build Removing toolchain in favour of compiler() Adding C compiler with mingw for windows

If you have recived a Migrate to Jinja2 compiler syntax PR from me recently please close that one and use this one. Notes and instructions for merging this PR:

1. Please merge the PR only after the tests have passed.
2. Feel free to push to the bot's branch to update this PR if needed. If you would like a local version of this bot, you might consider using rever. Rever is a tool for automating software releases and forms the backbone of the bot's conda-forge PRing capability. Rever is both conda (conda install -c conda-forge rever) and pip (pip install re-ver) installable.

Finally, feel free to drop us a line if there are any issues!

[conda-forge-linter]

Hi! This is the friendly automated conda-forge-linting service.

I just wanted to let you know that I linted all conda-recipes in your PR (recipe) and found it was in an excellent condition.

[pkgw]

Ah, the proximate problem seems to be that $VS_MAJOR is no longer set as an environment variable. The conda-build docs say that it should be. Is this an oversight in conda-forge's infrastructure? Are the docs no longer operative?

[pkgw]

One last force-push with cleaned up history ...