Publish quay.io/pypa/manylinux2010_centos-6-no-vsyscall

[mayeut]

Now that CentOS 6 is EOL, I don't expect the base image used for manylinux2010_x86_64 quay.io/pypa/manylinux2010_centos-6-no-vsyscall to ever change and it might be time to publish it.

It will decrease build time & simplify build scripts.

Pre-requisite: #874

@pypa/manylinux, any thought ? Shall it be renamed ?

[rdb]

It is currently impossible for anyone to actually build manylinux2010 from the repository without first building the glibc base images:

Sending build context to Docker daemon  19.28MB
Step 1/25 : FROM quay.io/pypa/manylinux2010_centos-6-no-vsyscall
unauthorized: access to the requested resource is not authorized

Any chance this could be fixed? It would make building manylinux2010 more convenient.

[mayeut]

@rdb, This will be fixed shortly. If you are rebuilding manylinux2010 on your end for whatever reason, you might be interested in #877 that will end up changing some things for you.

xref #481 (issues caused by the base image not being published)