I too am having the same problem.  I ran your script on my host and it does show mysql and mysqli.  I cant figure it out....

 

Array ( [0] => Core [1] => date [2] => ereg [3] => libxml [4] => openssl [5] => pcre [6] => sqlite3 [7] => zlib [8] => bz2 [9] => calendar [10] => ctype [11] => curl [12] => hash [13] => filter [14] => ftp [15] => gettext [16] => gmp [17] => SPL [18] => iconv [19] => pcntl [20] => readline [21] => Reflection [22] => session [23] => standard [24] => shmop [25] => SimpleXML [26] => mbstring [27] => tokenizer [28] => xml [29] => cgi-fcgi [30] => bcmath [31] => dom [32] => fileinfo [33] => gd [34] => imagick [35] => imap [36] => inotify [37] => intl [38] => json [39] => exif [40] => mcrypt [41] => mysql [42] => mysqli [43] => PDO [44] => pdo_mysql [45] => pdo_sqlite [46] => Phar [47] => posix [48] => soap [49] => xmlreader [50] => xmlrpc [51] => xmlwriter [52] => mhash )