Take the following code:
$formatter = new NumberFormatter('fr_FR', NumberFormatter::CURRENCY);
echo $formatter->formatCurrency('-1.23', 'EUR');
-1,23 €
(1,23 €)
libicu
libicu-50.1.2-15
libicu-57.1-4
PHP in "remi" repository (and AFAIK all 3rd party repositories) uses system libicu, as there is no bundled libicu in PHP.
(the only exception in packages in remi repository for EL-6 which use libicu 50, backported from EL-7 instead of default 4.2)