Add symbols for ray tracing

Author: jcmnn

crates/rustc_codegen_spirv/src/symbols.rs

@@ -137,6 +137,7 @@ const BUILTINS: &[(&str, BuiltIn)] = {
         ("ray_tmax", BuiltIn::RayTmaxKHR),
         ("object_to_world", BuiltIn::ObjectToWorldKHR),
         ("world_to_object", BuiltIn::WorldToObjectKHR),
+        ("hit_triangle_vertex_positions", BuiltIn::HitTriangleVertexPositionsKHR),
         ("hit_kind", BuiltIn::HitKindKHR),
         ("incoming_ray_flags", BuiltIn::IncomingRayFlagsKHR),
         ("warps_per_sm_nv", WarpsPerSMNV),