[clang] [riscv] Fix for __riscv_v_fixed_vlen in vector mask types (PR #76510)

[Craig Topper via cfe-commits]

topperc wrote:

I also have a patch for this that I started on 6 months ago. Let me dig it up and see how far along it was. I recall there being some tricky issues.

https://github.com/llvm/llvm-project/pull/76510