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%" '{}' \;
```

- Remove unused parameter `valobj` (I checked downstream, not
  even swift is using it).
- Return a std::pair<StringRef, StringRef> insted of having 2 out
  parameter strings.
- Remove the use of ConstStrings.

This change was primarily mechanical except in
`ObjCLanguage::GetFormatterPrefixSuffix`. To keep this fast, we
construct an llvm::StringMap<std::pair<StringRef, StringRef>> so that we
can look things up quickly. There is some amount of cost to setting up
the map the first time it is called, but subsequent lookups should be
as fast as a hash + string comparison (the cost of looking up something
in an llvm::StringMap).

Differential Revision: https://reviews.llvm.org/D151603

Currently, all data buffers are assumed to be writable. This is a
problem on macOS where it's not allowed to load unsigned binaries in
memory as writable. To be more precise, MAP_RESILIENT_CODESIGN and
MAP_RESILIENT_MEDIA need to be set for mapped (unsigned) binaries on our
platform.

Binaries are mapped through FileSystem::CreateDataBuffer which returns a
DataBufferLLVM. The latter is backed by a llvm::WritableMemoryBuffer
because every DataBuffer in LLDB is considered to be writable. In order
to use a read-only llvm::MemoryBuffer I had to split our abstraction
around it.

This patch distinguishes between a DataBuffer (read-only) and
WritableDataBuffer (read-write) and updates LLDB to use the appropriate
one.

rdar://74890607

Differential revision: https://reviews.llvm.org/D122856

Identifiers with __ anywhere are reserved. I picked this up via the
bugprone-reserved-identifier clang-tidy check but -Wreserved-identifier will
also flag these uses as well.

Differential Revision: https://reviews.llvm.org/D119915

The formatter was requesting an unsigned integer from the ValueObject,
but CFAbsoluteTime is a signed double, so in the NSDate test the formatter
actually just printed the 'error value' date which is the Cocoa epoch. This
started failing after the recent Scalar changes.

This patch just changes the logic to use a signed value which fits to the data
we try to read and avoids this issue.

Summary:
This change represents the move of ClangASTImporter, ClangASTMetadata,
ClangExternalASTSourceCallbacks, ClangUtil, CxxModuleHandler, and
TypeSystemClang from lldbSource to lldbPluginExpressionParserClang.h

This explicitly removes knowledge of clang internals from lldbSymbol,
moving towards a more generic core implementation of lldb.

Reviewers: JDevlieghere, davide, aprantl, teemperor, clayborg, labath, jingham, shafik

Subscribers: emaste, mgorny, arphaman, jfb, usaxena95, lldb-commits

Tags: #lldb

Differential Revision: https://reviews.llvm.org/D73661

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:
This commit renames ClangASTContext to TypeSystemClang to better reflect what this class is actually supposed to do
(implement the TypeSystem interface for Clang). It also gets rid of the very confusing situation that we have both a
`clang::ASTContext` and a `ClangASTContext` in clang (which sometimes causes Clang people to think I'm fiddling
with Clang's ASTContext when I'm actually just doing LLDB work).

I also have plans to potentially have multiple clang::ASTContext instances associated with one ClangASTContext so
the ASTContext naming will then become even more confusing to people.

Reviewers: #lldb, aprantl, shafik, clayborg, labath, JDevlieghere, davide, espindola, jdoerfert, xiaobai

Reviewed By: clayborg, labath, xiaobai

Subscribers: wuzish, emaste, nemanjai, mgorny, kbarton, MaskRay, arphaman, jfb, usaxena95, jingham, xiaobai, abidh, JDevlieghere, lldb-commits

Tags: #lldb

Differential Revision: https://reviews.llvm.org/D72684

Summary:
Following up to my CPPLanguageRuntime change, I'm moving
ObjCLanguageRuntime into a plugin as well.

Reviewers: JDevlieghere, compnerd, jingham, clayborg

Subscribers: mgorny, arphaman, lldb-commits

Differential Revision: https://reviews.llvm.org/D64763

llvm-svn: 366148

Summary:
In an effort to make Process more language agnostic, I removed
GetCPPLanguageRuntime from Process. I'm following up now with an equivalent
change for ObjC.

Differential Revision: https://reviews.llvm.org/D63052

llvm-svn: 362981