This commit makes ThreadMemory a real "forwarder" class by implementing
the missing queue methods: they will just call the corresponding backing
thread method.

To make this patch NFC(*) and not change the behavior of the Python OS
plugin, NamedThreadMemoryWithQueue also overrides these methods to
simply call the `Thread` method, just as it was doing before. This also
makes it obvious that there are missing pieces of this class if it were
to provide full queue support.

(*) This patch is NFC in the sense that all llvm.org plugins will not
have any behavior change, but downstream consumers of ThreadMemory will
benefit from the newly implemented forwarding methods.

ThreadMemory attempts to be a class abstracting the notion of a "fake"
Thread that is backed by a "real" thread. According to its
documentation, it is meant to be a class forwarding most methods to the
backing thread, but it does so only for a handful of methods.

Along the way, it also tries to represent a Thread that may or may not
have a different name, and may or may not have a different queue from
the backing thread. This can be problematic for a couple of reasons:

1. It forces all users into this optional behavior.
2. The forwarding behavior is incomplete: not all methods are currently
being forwarded properly. Some of them involve queues and seem to have
been intentionally left unimplemented.

This commit creates the following separation:

ThreadMemory <- ThreadMemoryProvidingName <-
ThreadMemoryProvidingNameAndQueue

ThreadMemory captures the notion of a backed thread that _really_
forwards all methods to the backing thread. (Missing methods should be
implemented in a later commit, and allowing them to be implemented
without changing behavior of other derived classes is the main purpose
of this refactor).

ThreadMemoryProvidingNameAndQueue is a ThreadMemory that allows users to
override the thread name. If a name is present, it is used; otherwise
the forwarding behavior is used.

ThreadMemoryProvidingNameAndQueue is a ThreadMemoryProvidingName that
allows users to override queue information. If queue information is
present, it is used; otherwise, the forwarding behavior is used.

With this separation, we can more explicitly implement missing methods
of the base class and override them, if needed, in
ThreadMemoryProvidingNameAndQueue. But this commit really is NFC, no new
methods are implemented and no method implementation is changed.

These prevented ThreadMemory from correctly returning the
Name/Queue/Info of the backing thread.

Note about testing: this test only finds regressions if the system sets
a name or queue for the backing thread. While this may not be true
everywhere, it still provides coverage in some systems, e.g. in Apple
platforms.

This enables finding the backed thread from the backing thread without
going through the thread list, and it will be useful for subsequent
commits.

Summary:
This is how I applied my clang-tidy check (see
https://reviews.llvm.org/D80531) in order to remove
`DISALLOW_COPY_AND_ASSIGN` and have deleted copy ctors and deleted
assignment operators instead.

```
lang=bash
grep DISALLOW_COPY_AND_ASSIGN /opt/notnfs/kkleine/llvm/lldb -r -l | sort | uniq > files

for i in $(cat files);
do
  clang-tidy \
    --checks="-*,modernize-replace-disallow-copy-and-assign-macro" \
    --format-style=LLVM \
    --header-filter=.* \
    --fix \
    -fix-errors \
    $i;
done
```

Reviewers: espindola, labath, aprantl, teemperor

Reviewed By: labath, aprantl, teemperor

Subscribers: teemperor, aprantl, labath, emaste, sbc100, aheejin, MaskRay, arphaman, usaxena95, lldb-commits

Tags: #lldb

Differential Revision: https://reviews.llvm.org/D80543

LLDB has a few different styles of header guards and they're not very
consistent because things get moved around or copy/pasted. This patch
unifies the header guards across LLDB and converts everything to match
LLVM's style.

Differential revision: https://reviews.llvm.org/D74743

to reflect the new license.

We understand that people may be surprised that we're moving the header
entirely to discuss the new license. We checked this carefully with the
Foundation's lawyer and we believe this is the correct approach.

Essentially, all code in the project is now made available by the LLVM
project under our new license, so you will see that the license headers
include that license only. Some of our contributors have contributed
code under our old license, and accordingly, we have retained a copy of
our old license notice in the top-level files in each project and
repository.

llvm-svn: 351636

This patch removes the comments grouping header includes. They were
added after running IWYU over the LLDB codebase. However they add little
value, are often outdates and burdensome to maintain.

llvm-svn: 346626

It was returning const std::string& which was leading to
unnecessary copies all over the place, and preventing people
from doing things like Dict->GetValueForKeyAsString("foo", ref);

llvm-svn: 302875

*** to conform to clang-format’s LLVM style.  This kind of mass change has
*** two obvious implications:

Firstly, merging this particular commit into a downstream fork may be a huge
effort.  Alternatively, it may be worth merging all changes up to this commit,
performing the same reformatting operation locally, and then discarding the
merge for this particular commit.  The commands used to accomplish this
reformatting were as follows (with current working directory as the root of
the repository):

    find . \( -iname "*.c" -or -iname "*.cpp" -or -iname "*.h" -or -iname "*.mm" \) -exec clang-format -i {} +
    find . -iname "*.py" -exec autopep8 --in-place --aggressive --aggressive {} + ;

The version of clang-format used was 3.9.0, and autopep8 was 1.2.4.

Secondly, “blame” style tools will generally point to this commit instead of
a meaningful prior commit.  There are alternatives available that will attempt
to look through this change and find the appropriate prior commit.  YMMV.

llvm-svn: 280751