[llvm] [RISCV] Use 'riscv-isa' module flag to set ELF flags and attributes. (PR #85155)

[Craig Topper via llvm-commits]

topperc wrote:

> @topperc should this be cherry-picked into the llvm 18 release branch?

I guess it would be nice, but its not fixing a regression from a previous version so I'm not sure if it would be accepted this late.

https://github.com/llvm/llvm-project/pull/85155