Version 2 was added more than two years ago
(https://github.com/llvm/llvm-project/commit/6015a045d768feab3bae9ad9c0c81e118df8b04a).
So it should be safe to deprecate older versions.

Recently, we have been looking at some optimizations targeting
individual calls. In particular, we plan to extend the address mapping
technique to map to individual callsites. For example, in this piece of
code for a basic blocks:

```
<BB>:
1200:    lea 0x1(%rcx), %rdx
1204:    callq foo
1209:    cmpq 0x10, %rdx
120d:    ja  L1
```

We want to emit 0x9 as the call site offset for `callq foo` (the offset
from the block entry to right after the call), so that we know if a
sampled address is before the call or after.

This PR implements the decode/encode/emit capability. The Codegen change
will be implemented in a later PR.

This is just a stub for now.

Values sourced from binutils.

gfx940 and gfx941 are no longer supported. This is one of a series of
PRs to remove them from the code base.

This PR removes all non-documentation occurrences of gfx940/gfx941 from
the llvm directory, and the remaining occurrences in clang.

Documentation changes will follow.

For SWDEV-512631

Add support for the new SHF_AARCH64_PURECODE ELF section flag:
https://github.com/ARM-software/abi-aa/pull/304

The general implementation follows the existing one for ARM targets.
Generating object files with the `SHF_AARCH64_PURECODE` flag set is
enabled by the `+execute-only` target feature.

Related PRs:
* Clang: https://github.com/llvm/llvm-project/pull/125688
* LLD: https://github.com/llvm/llvm-project/pull/125689

Alternative to #123137

With -DMACHINE=EM_NONE, machine specific
sections, like SHT_ARM_EXIDX, will fall to parse
and set `Type`.

This triggers msan on
```
yaml2obj llvm-project/llvm/test/tools/yaml2obj/ELF/mips-abi-flags.yaml -DMACHINE=EM_NONE
```

Size is required, so we don't know if it's in
uninitialized state after the previous error.

Triggers msan on llvm/test/tools/yaml2obj/ELF/custom-fill.yaml NOSIZE
test.

We have `Fill` Section with Pattern, but no size. Before the fix it
produced error:
```
YAML:169:5: error: missing required key 'Size'
  - Type:    Fill
    ^
YAML:169:5: error: "Size" can't be 0 when "Pattern" is not empty
  - Type:    Fill
```

The same applies to `MachOYAML::Section` fields `content` and `size`.
However `MachOYAML::Section` matches size first, so on error,
content is not set anyway. Added error checking just in case.

Reverts llvm/llvm-project#123137

It's a bug according to
https://github.com/llvm/llvm-project/pull/123137#pullrequestreview-2555328813

It will not be set if:

1. `(TypeStr.starts_with("SHT_") || isInteger(TypeStr)) == false`: here
we want go to switch default.
2. `IO.mapRequired("Type", Type);` fail parsing. It sets error
internally, so probably not important what happen next, so it's go to
the switch