[llvm] [BranchFolding][RISCV] Optimize branches NE/EQ to zero or one (PR #131684)

[Michael Maitland via llvm-commits]

michaelmaitland wrote:

@topperc @mikhailramalho I have updated this patch to use optimizeCondBranch. In order to get it to work, we needed to update the PeepholeOptimizer to no longer preserve the CFG, DT, and LI, since we're possibly removing a successor from the CFG.

https://github.com/llvm/llvm-project/pull/131684