Ruby

Make the critical level an enum

Allocate singleton classes as namespaceable if their parent are

Shink RClass when it is known they can't be namespaced

Even when namespaces are enabled, only a few core classes created
during init will eventually be namespaced.

For these it's OK to allocate a 320B slot to hold the extra namespace
stuff.

But for any class created post init, we know we'll never need the...

Avoid creating namespace table for classes that can't be namespaced.

Ensure RCLASS_CLASSEXT_TBL accessor is always used.

Mark RClass instance that may be namespaced with RCLASS_NAMESPACEABLE

Optimize rb_namespace_available

Rather than to lazily check the env using a trinary
value, we can more straightforwardly check for the
env during the VM boot.

This allow rb_namespace_available to just be a pointer
dereference.

Merge blocks for the same condition

[rubygems/rubygems] Handle RubyGems installing to custom dir with non-existent parent dirs

https://github.com/rubygems/rubygems/commit/4701123601

[rubygems/rubygems] Handle Errno::EADDRNOTAVAIL gracefully

As showed by the unskiped spec, on Windows trying to use the 0.0.0.0
interface raises this error, and it's raised as a generic system error
when trying to create a bundler.lock file. Here's is a better place to...