EPCDebugObjectRegistrar is unused now that the ELF debugger support plugin uses AllocActions
https://github.com/llvm/llvm-project/pull/167866

## Purpose

This patch is one in a series of code-mods that annotate LLVM’s public
interface for export. This patch annotates the `llvm/ExecutionEngine`
library. These annotations currently have no meaningful impact on the
LLVM build; however, they are a prerequisite to support an LLVM Windows
DLL (shared library) build.

## Background

This effort is tracked in #109483. Additional context is provided in
[this
discourse](https://discourse.llvm.org/t/psa-annotating-llvm-public-interface/85307),
and documentation for `LLVM_ABI` and related annotations is found in the
LLVM repo
[here](https://github.com/llvm/llvm-project/blob/main/llvm/docs/InterfaceExportAnnotations.rst).

The bulk of these changes were generated automatically using the
[Interface Definition Scanner (IDS)](https://github.com/compnerd/ids)
tool, followed formatting with `git clang-format`.

The following manual adjustments were also applied after running IDS on
Linux:
- Add `LLVM_ABI_FRIEND` to friend member functions declared with
`LLVM_ABI`
- Add `LLVM_ABI` to a subset of private class methods and fields that
require export
- Add `LLVM_ABI` to a small number of symbols that require export but
are not declared in headers
- Add `LLVM_ABI` to a number of `extern "C"` methods that IDS missed
because they're implicitly exported

## Validation

Local builds and tests to validate cross-platform compatibility. This
included llvm, clang, and lldb on the following configurations:

- Windows with MSVC
- Windows with Clang
- Linux with GCC
- Linux with Clang
- Darwin with Clang

Identified with misc-include-cleaner.

Use LLVM_ALWAYS_EXPORT for __jit_debug_descriptor and
__jit_debug_register_code so there exported even if LLVM is not built as
a shared library.

This is part of the work to enable LLVM_BUILD_LLVM_DYLIB and plugins on
windows #109483.

If you build LLVM with `-DCMAKE_CXX_VISIBILITY_PRESET=hidden` to help
reduce binary size, these symbols end up becoming local, and getting
stripped. This forces default visibility to override the global setting
in that case.

Relevant:
https://github.com/llvm/llvm-project/issues/62815#issuecomment-1560078260

https://github.com/llvm/llvm-project/pull/76236 introduced the forth
copy and it was time to deduplicate. This patch brings it back to 2,
one in OrcTargetProcess and one in legacy ExecutionEngine.

Configure the plugin to automatically call the debugger rendezvous breakpoint `__jit_debug_register_code()` for every translation unit (enabled) or never at all (disabled). Default API and behavior remain unchanged.

If AutoRegisterCode is turned off, it's the client's own responsibility to call the rendezvous breakpoint function at an appropriate time.
Depending on the complexity of the debugger's rendezvous breakpoint implementation, this can provide significant performance improvements in cases where many debug objects are added in sequence.

Reviewed By: lhames

Differential Revision: https://reviews.llvm.org/D147310

This change originally landed as part of
e6f1f062457c928c18a88c612f39d9e168f65a85 (D129120), which caused a
Fuchsia buildbot regression in ExecutionEngine tests.

I am resubmitting the backed out parts in smaller pieces after a careful
review.

This reverts commit e6f1f062457c928c18a88c612f39d9e168f65a85.

Reverting due to a failure on the fuchsia-x86_64-linux buildbot.