Remove Makefile

[leezu]

Replaced by cmake build. See #16167

[mxnet-bot]

Hey @leezu , Thanks for submitting the PR
All tests are already queued to run once. If tests fail, you can trigger one or more tests again with the following commands:

• To trigger all jobs: @mxnet-bot run ci [all]
• To trigger specific jobs: @mxnet-bot run ci [job1, job2]

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CI supported jobs: [centos-cpu, clang, unix-gpu, sanity, windows-cpu, unix-cpu, miscellaneous, centos-gpu, website, edge, windows-gpu]

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Note:
Only following 3 categories can trigger CI :PR Author, MXNet Committer, Jenkins Admin.
All CI tests must pass before the PR can be merged.

[leezu]

@mxnet-bot run ci [centos-cpu]

[mxnet-bot]

Jenkins CI successfully triggered : [centos-cpu]

[leezu]

@mxnet-bot run ci [all]

[mxnet-bot]

Jenkins CI successfully triggered : [edge, sanity, unix-cpu, miscellaneous, unix-gpu, centos-gpu, windows-cpu, clang, website, centos-cpu, windows-gpu]

[szha]

Developers may still need to rely on some of the Makefile targets for development purpose. Make sure that they are documented prominently, as we can't ask developers to read the CI code first when starting with out project.

[leezu]

The Makefile targets are undocumented and are tied to the CI:

https://github.com/apache/incubator-mxnet/blob/faccd91071cc34ed0b3a192d3c7932441fe7e35e/ci/docker/install/requirements#L35-L36

For now using the python ci/build.py --platform ubuntu_cpu /work/runtime_functions.sh sanity_check or manually running pylint and cpplint should be acceptable. We can have a separate PR that removes the technical debt of the linting system (#17968 (comment)). For pylint, just moving ci/other/pylintrc to the root of the repo should be sufficient. For cpplint, we need to migrate to clang-format and cmake will run it automatically.

[szha]

Thanks for elaborating. Would you update the document here to reflect this? https://cwiki.apache.org/confluence/display/MXNET/Development+Process
https://cwiki.apache.org/confluence/pages/viewpage.action?pageId=125309983&src=contextnavpagetreemode

There probably are a number of other pages that reference the use of make that we should clean up. Searching in cwiki should reveal them.

[leezu]

I updated the https://cwiki.apache.org/confluence/display/MXNET/Development+Process and
https://cwiki.apache.org/confluence/pages/viewpage.action?pageId=125309983&src=contextnavpagetreemode
Searching through the wiki didn't yield other obvious references to the Makefile