The MONGOC_ENABLE_ICU constant was removed in PHPC-2262, when ICU was replaced with utf8proc. Since libmongoc 1.25 also introduced MONGOC_ENABLE_SRV, we should just replace the ICU reporting with SRV.

Note: both are unrelated and just coincidentally occurred in the same release.

remi opened a PR for this (mongodb/mongo-php-driver#1490), which we can build upon.