Gentoo Checking User Problem

Now i have this error on line 746

Paranoia freepbx # ./install_amp
Checking for PEAR DB…OK
Checking for PEAR Console::Getopt…OK
Checking user…
Fatal error: Call to undefined function posix_getpwuid() in /var/www/localhost/htdocs/freepbx/install_amp on line 746

Here is the Code(line 746 is Bold):

// **** Look for user = root

outn(“Checking user…”);
//$current_user=(isset($_ENV[“USER”]) ? $_ENV[“USER”] : exec(‘whoami’,$output));
$euid = (posix_getpwuid(posix_geteuid()));
$current_user = $euid[‘name’];
if ($current_user != “root”){
fatal($argv[0]." must be run as root");

Solved by adding “posix” as a use flag for dev-lang/php on Gentoo