Reapply "[NFC][DebugInfo][DWARF] Create new low-level dwarf library (#…
(#145959)
    
This reapplies cbf781f0bdf2f680abbe784faedeefd6f84c246e, with fixes for
the shared-library build and the unconventional sanitizer-runtime build.

Original Description:

This is the culmination of a series of changes described in [1].
    
Although somewhat large by line count, it is almost entirely mechanical,
creating a new library in DebugInfo/DWARF/LowLevel. This new library has
very minimal dependencies, allowing it to be used from more places than
the normal DebugInfo/DWARF library--in particular from MC.
    
1.
https://discourse.llvm.org/t/rfc-debuginfo-dwarf-refactor-into-to-lower-and-higher-level-libraries/86665/2

…145081)"

This reverts commit cbf781f0bdf2f680abbe784faedeefd6f84c246e.

Breaks a couple of buildbots.

This is the culmination of a series of changes described in [1].
    
Although somewhat large by line count, it is almost entirely mechanical,
creating a new library in DebugInfo/DWARF/LowLevel. This new library has
very minimal dependencies, allowing it to be used from more places than
the normal DebugInfo/DWARF library--in particular from MC.
    
I am happy to put it in another location, or to structure it differently
if that makes sense. Some have suggested in BinaryFormat, but it is not
a great fit there. But if that makes more sense to the reviewers, I can
do that.
 
Another possibility would be to use pass-through headers to allow
clients who don't care to depend only on DebugInfo/DWARF. This would be
a much less invasive change, and perhaps easier for clients. But also a
system that hides details.

Either way, I'm open.

1.
https://discourse.llvm.org/t/rfc-debuginfo-dwarf-refactor-into-to-lower-and-higher-level-libraries/86665/2

This PR is in the direction of separating Unwind table from FDE, and CIE
that depends on llvm/Object.

To separate, first the runtime dependencies have to be removed, which
this commit does that.
This is similar to
[1](https://github.com/llvm/llvm-project/pull/140096),
[2](https://github.com/llvm/llvm-project/pull/139175), and
[3](https://github.com/llvm/llvm-project/pull/139326).

CFIPrograms' most common uses are within debug frames, but it is not
their only use. For example, some assembly writers encode them by hand
into .cfi_escape directives. This PR extracts printing code for them
into its own files, which avoids the need for the main class to depend
on DWARFUnit, sections, and similar.

One in a series of NFC DebugInfo/DWARF refactoring changes to layer it
more cleanly, so that binary CFI parsing can be used from low-level
code, (such as byte strings created via .cfi_escape) without circular
dependencies. The final goal is to make a more limited dwarf library
usable from lower-level code.

More information can be found at
https://discourse.llvm.org/t/rfc-debuginfo-dwarf-refactor-into-to-lower-and-higher-level-libraries/86665

(Revised version of a previous, unreviewed, PR.)

Move all expression verification into its only client: DWARFVerifier.
Move all printing code (which was a mix of static and member functions)
into a separate class.

This is one in a series of refactoring PRs to separate dwarf
functionality into lower-level pieces usable without object files and
sections at build time. The code is already written this way via various
"if (section == nullptr)" and similar conditionals. So the functionality
itself is needed and exists, but only as a runtime feature. The goal of
these refactors is to remove the build-time dependencies, which will
allow the existing functionality to be used from lower-level parts of
the compiler. Particularly from lib/MC/.... More information at:


https://discourse.llvm.org/t/rfc-debuginfo-dwarf-refactor-into-to-lower-and-higher-level-libraries/86665

CFIPrograms' most common uses are within debug frames, but it is not
their only use. For example, some assembly writers encode them by hand
into .cfi_escape directives. This PR extracts code for them into its own
files, setting them up to be evaluated from outside debug frames
themselves.

One in a series of NFC DebugInfo/DWARF refactoring changes to layer it
more cleanly, so that binary CFI parsing can be used from low-level
code, (such as byte strings created via .cfi_escape) without circular
dependencies. The final goal is to make a more limited dwarf library
usable from lower-level code.

Identified with misc-include-cleaner.

As part of FEAT_PAuthLR, a new DWARF Frame Instruction was introduced,
`DW_CFA_AARCH64_negate_ra_state_with_pc`. This instructs Libunwind that
the PC has been used with the signing instruction. This change includes
three commits
- Libunwind support for the newly introduced DWARF Instruction
- CodeGen Support for the DWARF Instructions
- Reversing the changes made in #96377. Due to
`DW_CFA_AARCH64_negate_ra_state_with_pc`'s requirements to be placed
immediately after the signing instruction, this would mean the CFI
Instruction location was not consistent with the generated location when
not using FEAT_PAuthLR. The commit reverses the changes and makes the
location consistent across the different branch protection options.
While this does have a code size effect, this is a negligible one.

For the ABI information, see here:
https://github.com/ARM-software/abi-aa/blob/853286c7ab66048e4b819682ce17f567b77a0291/aadwarf64/aadwarf64.rst#id23

When dumping FDEs, `readelf` prints new location values after
`DW_CFA_advance_loc(*)` instructions, which looks quite convenient:

```
> readelf -wf test.o
...
... FDE ... pc=0000000000000030..0000000000000064
  DW_CFA_advance_loc: 4 to 0000000000000034
  ...
  DW_CFA_advance_loc: 4 to 0000000000000038
...
```

This patch makes `llvm-dwarfdump` and `llvm-readobj` do the same.