spirv_backend: remove Vec3Std and use coremem_types::Vec3 everywhere

crates/spirv_backend/src/support.rs

@@ -1,11 +1,5 @@
-use coremem_types::vec;
 use coremem_types::vecu::Vec3u;
 
-#[derive(Clone, Copy, Default, PartialEq)]
-pub struct XYZStd<T>(T, T, T);
-
-pub type Vec3Std = vec::Vec3<f32>;
-
 /// This is a spirv-compatible option type.
 /// The native rust Option type produces invalid spirv due to its enum nature; this custom option
 /// type creates code which will actually compile.