[llvm] Support big endian in llvm-symbolizer's data location dwarf info parser (PR #67284)

[Chen Zheng via llvm-commits]

chenzheng1030 wrote:

> > Currently obj2yaml/yaml2obj can not support debug info for xcoff, so I used an object. Will update this once obj2yaml/yaml2obj are ready for XCOFF objects with DWARF info
> 
> Could you use some raw assembly & assemble it with llvm-mc, rather than a checked in object? That'd be a bit easier to maintain, maybe... (& if it's compiled from some higher level source - include that source and a command used to produce the assembly)

Yes, this would make more sense if we can generate the object from some kinds of source codes. However, we are also lacking XCOFF support in LLVM asm parser. For a very simple but fundamental assembly like below:
```
	.csect [PR],5
```

LLVM AsmParser reports `LLVM ERROR: XCOFFAsmParser directive not yet supported!`...

And very sorry about this. We(IBM power compiler team) have plans to support AIX assembly syntax in AsmParser, but this seems need a big effort and still not yet start.

https://github.com/llvm/llvm-project/pull/67284