[llvm] [llvm][ELF]Add Shdr check for getBuildID (PR #126537)

[Ruoyu Qiu via llvm-commits]

cabbaken wrote:

> Either way, I'm not asking for a huge object when I refer to the "largest valid size". The "valid" size I'm talking about is the size such that it points at the very last byte in a simple ELF object. One past the end is then invalid, because it points outside the file.

There are already checks in [`ELF.h`](https://github.com/llvm/llvm-project/blob/main/llvm/include/llvm/Object/ELF.h#L405), is it still necessary to implement a test for that?

https://github.com/llvm/llvm-project/pull/126537