Remove Doxygen configuration

Documentation for the SPL was once rendered at
http://www.php.net/~helly/php/ext/spl/

With upgrades of the PHP manual, the SPL documentation moved there
instead and PHP files for the SPL docs in the PHP source code directory
were outdated and removed via 9003d8a

Author: petk

.gitignore

@@ -171,9 +171,6 @@ ext/phar/phar.phar
 ext/phar/phar.1
 ext/phar/phar.phar.1
 ext/phar/phar.php
-ext/reflection/xml
-ext/reflection/html
-ext/reflection/spl.chm
 ext/spl/examples/.htaccess
 ext/spl/examples/*.phps
 ext/sqlite3/tests/phpsql*