running composer on xp(windows) results error 

Created project in libra-cms
Loading composer repositories with package information
Installing dependencies (including require-dev) from lock file
Warning: The lock file is not up to date with the latest changes in composer.jso
n. You may be getting outdated dependencies. Run update to update them.
Your requirements could not be resolved to an installable set of packages.

  Problem 1
    - Installation request for phpunit/php-invoker 1.1.3 -> satisfiable by phpun
it/php-invoker[1.1.3].
    - phpunit/php-invoker 1.1.3 requires ext-pcntl * -> the requested PHP extens
ion pcntl is missing from your system.