[llvm] [Coverage] Mark coverage sections as metadata sections on COFF. (PR #76834)

[Reid Kleckner via llvm-commits]

https://github.com/rnk commented:

Arthur, is there a better way to set section flags in LLVM IR, or at least a better place to store special case known section names to assign their characteristics?

cc @maskray , perhaps you have ideas

https://github.com/llvm/llvm-project/pull/76834