Co-authored-by: Nikita Popov <npopov@redhat.com>

## Purpose
Add proper preprocessor guards for all `dump()` methods in the LLVM
support library. This change ensures these methods are not part of the
public ABI for release builds.

## Overview
* Annotates all `dump` methods in Support and ADT source with the
`LLVM_DUMP_METHOD` macro.
* Conditionally includes all `dump` method definitions in Support and
ADT source so they are only present on debug/assert builds and when
`LLVM_ENABLE_DUMP` is explicitly defined.

NOTE: For many of these `dump` methods, the implementation was already
properly guarded but the declaration in the header file was not.

## Background
This PR is a redo of #139804 with some changes to fix clang and unit
test build breaks.

This issue was raised in comments on #136629. I am addressing it as a
separate change since it is independent from the changes being made in
that PR.

According to [this
documentation](https://github.com/llvm/llvm-project/blob/main/llvm/include/llvm/Support/Compiler.h#L637),
`dump` methods should be annotated with `LLVM_DUMP_METHOD` and
conditionally included as follows:
```
#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
  LLVM_DUMP_METHOD void dump() const;
#endif
```

## Validation
* Local release build succeeds.
* CI

Reverts llvm/llvm-project#139804

## Purpose
Add proper preprocessor guards for all `dump()` methods in the LLVM
support library. This change ensures these methods are not part of the
public ABI for release builds.

## Overview
* Annotates all `dump` methods in Support and ADT source with the
`LLVM_DUMP_METHOD` macro.
* Conditionally includes all `dump` method definitions in Support and
ADT source so they are only present on debug/assert builds and when
`LLVM_ENABLE_DUMP` is explicitly defined.

NOTE: For many of these `dump` methods, the implementation was already
properly guarded but the declaration in the header file was not.

## Background
This issue was raised in comments on #136629. I am addressing it as a
separate change since it is independent from the changes being made in
that PR.

According to [this
documentation](https://github.com/llvm/llvm-project/blob/main/llvm/include/llvm/Support/Compiler.h#L637),
`dump` methods should be annotated with `LLVM_DUMP_METHOD` and
conditionally included as follows:
```
#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
  LLVM_DUMP_METHOD void dump() const;
#endif
```

## Validation
* Local release build succeeds.
* CI

Co-authored-by: Nikita Popov <github@npopov.com>

startswith/endswith wrap starts_with/ends_with and will eventually go away (to more closely match string_view)

[Re-submit after earlier revert due to a test failure. Commit dce78646f07
("clang-tblgen build: avoid duplicate inclusion of libLLVMSupport")
is believe to address the root cause of the test failure.]

Follow the pattern used in MLIR for the cl::opt instances.

v2:
- make DebugCounter::isCountingEnabled public so that the
  DebugCounterOwner doesn't have to be a nested class. This simplifies
  later changes

v3:
- remove the indirection via DebugCounterOwner::instance()

Differential Revision: https://reviews.llvm.org/D129116

This reverts commit b5b6ef1500af29b6aba71330d8aaf82ecccb1f37.

Follow the pattern used in MLIR for the cl::opt instances.

v2:
- make DebugCounter::isCountingEnabled public so that the
  DebugCounterOwner doesn't have to be a nested class. This simplifies
  later changes

v3:
- remove the indirection via DebugCounterOwner::instance()

Differential Revision: https://reviews.llvm.org/D129116