[llvm] [RISCV] Place mergeable small read only data into srodata section (PR #82214)

[Paul Kirth via llvm-commits]

https://github.com/ilovepi approved this pull request.

LGTM from my perspective, and I agree this seems likely to address the issue raised in https://bugs.chromium.org/p/llvm/issues/detail?id=61 . In Fuchsia, we set `-msmall-data-limit=0` everywhere, in part due to that, but that isn't the only concern. We've set that for a long time, in part due to our use of the Shadow Call Stack, and some interactions w/ small data limit were not desirable. I'm not completely sure if those still exists, though. So I agree w/ @MaskRay 's suggestion about choosing a different default, though that is an orthogonal question.

https://github.com/llvm/llvm-project/pull/82214