This patch removes all of the Set.* methods from Status.

This cleanup is part of a series of patches that make it harder use the
anti-pattern of keeping a long-lives Status object around and updating
it while dropping any errors it contains on the floor.

This patch is largely NFC, the more interesting next steps this enables
is to:
1. remove Status.Clear()
2. assert that Status::operator=() never overwrites an error
3. remove Status::operator=()

Note that step (2) will bring 90% of the benefits for users, and step
(3) will dramatically clean up the error handling code in various
places. In the end my goal is to convert all APIs that are of the form

`    ResultTy DoFoo(Status& error)
`
to

`    llvm::Expected<ResultTy> DoFoo()
`
How to read this patch?

The interesting changes are in Status.h and Status.cpp, all other
changes are mostly

` perl -pi -e 's/\.SetErrorString/ = Status::FromErrorString/g' $(git
grep -l SetErrorString lldb/source)
`
plus the occasional manual cleanup.

This option doesn't exist. It is currently displayed by `help target
var` due to a bug introduced by 41ae8e7445 in 2018.

Some code for `target var` and `frame var` is shared, and some hard-code
constants are used in order to filter out options that belong only to
`frame var`. However, the aforementioned commit failed to update these
constants properly. This patch addresses the issue by having a _single_
place where the filtering of options needs to be done.

This is a follow-up to https://reviews.llvm.org/D140896, split into
several parts as it touches a lot of files.

Differential Revision: https://reviews.llvm.org/D141298

Improve LLDB reliability by fixing the following "uninitialized variables" static code inspection warnings from
scan.coverity.com/projects/llvm:

1355854, 1347549, 1316348, 1372028, 1431625,
1315634, 1315637, 1355855, 1364803, 1420505,
1420563, 1420685, 1366014, 1203966, 1204029,
1204031, 1204032, 1328411, 1325969, 1325968,
1374921, 1094809

Differential Revision: https://reviews.llvm.org/D130602

According to clang-tidy's readability-redundant-member-init.

Summary:
A *.cpp file header in LLDB (and in LLDB) should like this:
```
//===-- TestUtilities.cpp -------------------------------------------------===//
```
However in LLDB most of our source files have arbitrary changes to this format and
these changes are spreading through LLDB as folks usually just use the existing
source files as templates for their new files (most notably the unnecessary
editor language indicator `-*- C++ -*-` is spreading and in every review
someone is pointing out that this is wrong, resulting in people pointing out that this
is done in the same way in other files).

This patch removes most of these inconsistencies including the editor language indicators,
all the different missing/additional '-' characters, files that center the file name, missing
trailing `===//` (mostly caused by clang-format breaking the line).

Reviewers: aprantl, espindola, jfb, shafik, JDevlieghere

Reviewed By: JDevlieghere

Subscribers: dexonsmith, wuzish, emaste, sdardis, nemanjai, kbarton, MaskRay, atanasyan, arphaman, jfb, abidh, jsji, JDevlieghere, usaxena95, lldb-commits

Tags: #lldb

Differential Revision: https://reviews.llvm.org/D73258

Summary:
We currently have a bunch of code that is supposed to handle invalid command options, but
all this code is unreachable because invalid options are already handled in `Options::Parse`.
The only way we can reach this code is when we declare but then not implement an option
(which will be made impossible with D65386, which is also when we can completely remove
the `default` cases).

This patch replaces all this code with `llvm_unreachable` to make clear this is dead code
that can't be reached.

Reviewers: JDevlieghere

Reviewed By: JDevlieghere

Subscribers: lldb-commits

Tags: #lldb

Differential Revision: https://reviews.llvm.org/D66522

llvm-svn: 369625

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 simplifies boolean expressions acorss LLDB. It was generated
using clang-tidy with the following command:

run-clang-tidy.py -checks='-*,readability-simplify-boolean-expr' -format -fix $PWD

Differential revision: https://reviews.llvm.org/D55584

llvm-svn: 349215