Ya hice get_include_path() y ini_get('include_path') y daba ese resultado.
En el warning, dice:
Cita: (include_path='/var/www/clients/client0/web2/web:/var/www/clients/client0/web2/web/phpost/inc/php:./phpost/inc/php') in /var/www/clients/client0/web2/web/phpost/inc/php/perfil.php on line 24
include_path='/var/www/clients/client0/web2/web:/var/www/clients/client0/web2/web/phpost/inc/php:./phpost/inc/php'
Y el script: /var/www/clients/client0/web2/web/phpost/inc/php/perfil.php