Building went well as usual but when I tried to integrate the extension inside php.ini it was all weird. When loading it with

zend_extension=xdebug.so

the error log told me:

Failed loading xdebug.so: xdebug.so: cannot open shared object file: No such file or directory.

The extension_dir has been properly configured in php.ini and I also have the xdebug.so file in the right place. When loading Xdebug as a normal extension everything went entirely well:

extension=xdebug.so

But I need to enable it as Zend extension. Whatever. I finally used the full path to xdebug.so to load it:

zend_extension=/path/to/extension_dir/xdebug.so

That worked. But do I have to give a full path here?