Integrate LLVM at llvm/llvm-project@76a3be7c766b
Integrate LLVM at llvm/llvm-project@76a3be7c766b

Updates LLVM usage to match
[76a3be7c766b](https://github.com/llvm/llvm-project/commit/76a3be7c766b)

FUTURE_COPYBARA_INTEGRATE_REVIEW=https://github.com/openxla/xla/pull/11717 from Cjkkkk:remove_fused_attn_and_mask ff1952faa460eecfca62660a5c34ea6fa3c2dfd4
