It is considered bad form to use things from includes in headers, as
these directives propagate to everywhere else and can make it
confusing.
types.hh (which is includes almost literally everywhere) had some of
these directives, which this commit removes.
Externally developed dependencies which have been imported ("vendored") into
this repository. These dependencies come with their own licenses and whatever
else.
Code that is developed inside of this repository, but released to an external
repository via Copybara.
838f86b0fd