[php-src] Issue #11596: Default extension location for Windows relative to php.exe

Issue: https://github.com/php/php-src/issues/11596 Author: crowne ### Description Please can the default extension location be set to the ext directory in the same directory as the php.exe It seems that the default location without an ini file loaded is extension_dir => C:\php\ext => C:\php\ext That would work if php was installed in C:\php But not if its installed in C:\util\php or C:/php5.6.4 see related [issue](https://stackoverflow.com/questions/28122051/php-extension-is-in-a-different-location). I know that the extension location can be specified in the php.ini, however usage of sensible default values can prevent superflous/unnecessary configuration