Disable simd_clamp test on ppc64

crates/core_simd/tests/ops_macros.rs

@@ -514,6 +514,8 @@ macro_rules! impl_float_tests {
                     assert!(n_zero.simd_max(p_zero).to_array().iter().all(|x| *x == 0.));
                 }
 
+                #[cfg(not(all(target_arch = "powerpc64", target_feature = "vsx")))]
+                // https://gitlab.com/qemu-project/qemu/-/issues/1780
                 fn simd_clamp<const LANES: usize>() {
                     test_helpers::test_3(&|value: [Scalar; LANES], mut min: [Scalar; LANES], mut max: [Scalar; LANES]| {
                         use test_helpers::subnormals::flush_in;