eea3ed6a37
`lp_build_round` intends to implement round with ties-to-even behavior,
as can be seen by its test's use of `nearbyint` to generate reference
values and by it use in implementing `nir_op_fround_even`.
Fixes: 0d3b285360 ("gallivm: use llvm intrinsics for 16-bit round/trunc/roundeven")
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/34937>