GN r295316 binary pushed

[Brett Wilson]

I just pushed GN r295316 that changes how dependent configs work (this
is in a separate push from last night's because of the risk).

"direct_dependent_configs" is renamed "public_configs". It has the
same meaning. For now, both are supported.

I just added a new variable called "public_deps" which will replace
"forward_dependent_configs_from". Public deps are more lax than
forward_dependent_configs_from in that they also give dependents the
power to include header files from those dependencies. But they're
more strict in that targets without direct_dependent_/public_configs
will no longer be implicitly part of the API of a target.

I plan to remove "forward_dependent_configs_from" when everything is
eventually converted.

In practice, this will mean that the "gn check" output will complain
about lots of things it didn't before because we need to convert deps
to public_deps. But it will also allow us to express "you can use
headers from a target via an intermediate one, but don't depend
directly on the target with the headers" which came up surprisingly
often.