No ctng and build GCC 10, 11

[isuruf]

cc @beckermr, @chenghlee, @katietz, @ocefpaf

This is the first to step to remove crosstool-ng and build gcc directly using ./configure && make.

The reason to remove crosstool-ng is it's hard to work with and building cross-native or canadian cross compilers is hard. (It's possible, but hard). It's also building the sysroot and binutils redundantly because we build them elsewhere.

I've only added the bare minimum to make this work. I intend to do some more refactoring like ctng_gcc->gcc_version , but
I've hold off on that to make the review easier. (I'll also add cross-native compilers in a separate PR)

I've also added conda-forge/label/gcc_dev so that these compilers are not uploaded to main right now, so that I can play with
them for a while. When this PR is ready to be merged, I'll make a gcc-feedstock through staged-recipes.

Closes #50
Fixes #55

[conda-forge-linter]

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

I wanted to let you know that I linted all conda-recipes in your PR (recipe) and found some lint.

Here's what I've got...

For recipe:

• When defining a source/url please add a sha256, sha1 or md5 checksum (sha256 preferably).

[beckermr]

Great work!

My main concern here is that we will get a different layout of the files between the different split packages and that will break the compilers if we mix stuff built by crosstool-ng and the gcc build.

It looks like you beefed up the tests a bit to make sure each package has the files it is supposed to have. Should we do more of that?

[isuruf]

My main concern here is that we will get a different layout of the files between the different split packages and that will break the compilers if we mix stuff built by crosstool-ng and the gcc build.

The differences are in gcc_impl, gxx_impl, libgcc_devel, libstdcxx_devel which pin each other exactly. So I don't think mixing is possible.
We'll be bumping the gcc minor versions 9.3.0->9.4.0 when publishing these and different versions cannot be mixed anyway. (Note that the channel_target is conda-forge/label/gcc_dev)

[beckermr]

Ahhh great! Then as long as the compilers work, we should be good to go!

[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.

[beckermr]

Do we still want to keep the -ng in the package names? Maybe we remove once a new gcc feedstock is created?

[isuruf]

I don't mind keeping it as it might be disruptive to remove. Besides I don't think -ng is about crosstool-ng, but just new generation.

[isuruf]

Let me know if you think this is good to merge and I'll fix some things up and merge.

[beckermr]

LGTM!