[llvm] DWARF: Emit `DW_AT_artificial` on artificial globals (PR #93118)

[Adrian Prantl via llvm-commits]

adrian-prantl wrote:

> I do wonder whether DILocalVariable really needs a whole DIFlags member; it might be worth auditing which flags it actually uses, and maybe we're better off with independent bool fields like DIGlobalVariable has. DILocalVariable has only two member functions that query specific flags, one of which is the Artificial flag that we want to be in common with DIGlobalVariable now.

Seems like a reasonable thing to do. The current layout with the shared DIFlags exists purely for historical reasons of how the data structure evolved over time.

https://github.com/llvm/llvm-project/pull/93118