addCSourceFiles

fn addCSourceFiles(s: *Serialize, csf: *const std.Build.Module.CSourceFiles) !Configuration.CSourceFiles.Index {
    const wc = s.wc;
    const sub_paths = try initStringList(s, csf.files);
    const args = try initStringList(s, csf.flags);
    return try wc.addExtra(Configuration.CSourceFiles, .{
        .flags = .{
            .args_len = @intCast(args.len),
            .lang = .init(csf.language),
        },
        .root = try addLazyPath(s, csf.root),
        .sub_paths = .{ .slice = sub_paths },
        .args = .{ .slice = args },
    });
}