This patch should be mostly obvious, but in one place, this patch
changes:

  const auto &it = std::find(...)

to:

  auto it = llvm::find(...)

We do not need to bind to a temporary with const ref.

Expressions can take arbitrary amounts of time to run, so IDEs might
want to be informed about the fact that an expression is currently being
executed.

rdar://141253078

ValueObject is part of lldbCore for historical reasons, but conceptually
it deserves to be its own library. This does introduce a (link-time) circular
dependency between lldbCore and lldbValueObject, which is unfortunate
but probably unavoidable because so many things in LLDB rely on
ValueObject. We already have cycles and these libraries are never built
as dylibs so while this doesn't improve the situation, it also doesn't
make things worse.

The header includes were updated with the following command:

```
find . -type f -exec sed -i.bak "s%include \"lldb/Core/ValueObject%include \"lldb/ValueObject/ValueObject%" '{}' \;
```

and implement them for dwim-print (a.k.a. `p`) as an example.

The next step will be to expose them as structured data in
SBCommandReturnObject.

We have 3 different enums all expressing severity (info, warning,
error). Remove all uses with a new Severity enum in lldb-enumerations.h.

We generally prohibit this at a higher level - for instance requiring
the process to be stopped for "expr".  But when we trigger an expression
for internal purposes (e.g. to fetch types from the ObjC runtime) we weren't
checking the process state.  Now we explicitly check this at the very start
of the job so we don't get into bad states.

Differential Revision: https://reviews.llvm.org/D137684

Resubmission of https://reviews.llvm.org/D130309 with the 2 patches that fixed the linux buildbot, and new windows fixes.

The FileSpec APIs allow users to modify instance variables directly by getting a non const reference to the directory and filename instance variables. This makes it impossible to control all of the times the FileSpec object is modified so we can clear cached member variables like m_resolved and with an upcoming patch caching if the file is relative or absolute. This patch modifies the APIs of FileSpec so no one can modify the directory or filename instance variables directly by adding set accessors and by removing the get accessors that are non const.

Many clients were using FileSpec::GetCString(...) which returned a unique C string from a ConstString'ified version of the result of GetPath() which returned a std::string. This caused many locations to use this convenient function incorrectly and could cause many strings to be added to the constant string pool that didn't need to. Most clients were converted to using FileSpec::GetPath().c_str() when possible. Other clients were modified to use the newly renamed version of this function which returns an actualy ConstString:

ConstString FileSpec::GetPathAsConstString(bool denormalize = true) const;

This avoids the issue where people were getting an already uniqued "const char *" that came from a ConstString only to put the "const char *" back into a "ConstString" object. By returning the ConstString instead of a "const char *" clients can be more efficient with the result.

The patch:
- Removes the non const GetDirectory() and GetFilename() get accessors
- Adds set accessors to replace the above functions: SetDirectory() and SetFilename().
- Adds ClearDirectory() and ClearFilename() to replace usage of the FileSpec::GetDirectory().Clear()/FileSpec::GetFilename().Clear() call sites
- Fixed all incorrect usage of FileSpec::GetCString() to use FileSpec::GetPath().c_str() where appropriate, and updated other call sites that wanted a ConstString to use the newly returned ConstString appropriately and efficiently.

Differential Revision: https://reviews.llvm.org/D130549

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