update to latest std Thread API

tools/update_cpu_features.zig

@@ -786,13 +786,13 @@ pub fn main() anyerror!void {
     } else {
         var threads = try arena.alloc(*std.Thread, llvm_targets.len);
         for (llvm_targets) |llvm_target, i| {
-            threads[i] = try std.Thread.spawn(Job{
+            threads[i] = try std.Thread.spawn(processOneTarget, .{
                 .llvm_tblgen_exe = llvm_tblgen_exe,
                 .llvm_src_root = llvm_src_root,
                 .zig_src_dir = zig_src_dir,
                 .root_progress = root_progress,
                 .llvm_target = llvm_target,
-            }, processOneTarget);
+            });
         }
         for (threads) |thread| {
             thread.wait();