RFC: 8247976: Update HotSpot Style Guide for C++14 adoption

[Kim Barrett]

Please review / comment on this proposed update to the HotSpot Style
Guide. This is part of the work for JDK-8208089: JEP 347: Adopt C++14
Language Features in the JDK.

This update includes additions for initial C++14 adoption. It has also
been significantly refactored and modified from the current wiki text.
There have long been complaints that what's on the wiki hasn't kept up
with actual usage. I've also added more explanation and rationale for
some parts, based on (sometimes repeated) discussions in various
forums. (Note that I might not always entirely agree with some
choices, but I've tried to fairly and accurately record what I think
is the rationale. Feel free to offer corrections.)

For convenience of review, especially for incremental updates based on
feedback, I'm publishing the updated document as a webrev. Once
reviewed, the finished text can be used to update the wiki, unless we
decide it should be homed somewhere else.

We don't currently have a process for making updates to this document
(one reason for it falling out of date). This update includes a
proposal for such a process, but that process may need approvals from
elsewhere, and there's the whole bootstrapping question. We'll see how
this goes; maybe there won't be any complaints and it's done. That's
likely wishful thinking.

To see the html-formatted version you'll probably need to download and
view it locally; cr.openjdk.java.net doesn't seem to like serving it
from the webrev.

CR:
https://bugs.openjdk.java.net/browse/JDK-8247976

Webrev:
https://cr.openjdk.java.net/~kbarrett/8247976/hotspot-style.00/