PHP is removing POSIX regular expressions and replacing it with Perl based regular expressions.  All that says is the function, eregi(), which uses POSIX regular expressions is going to be removed in future versions of PHP.  Doesn't mean the code is broken but the programmer needs to use preg_match() instead of eregi().  

If you want to remove the error you need to turn off E_DEPRECATED for error_reporting in php.ini.

error_reporting  =  E_ALL &amp; ~E_DEPRECATED

Or turn off error_reporting all together.