ZTS fixes for PDO

http://www.sebastian-bergmann.de/stuff/pdo-zts.txt

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Sebastian Bergmann http://www.sebastian-bergmann.de/
GnuPG Key: 0xB85B5D69 / 27A7 2B14 09E4 98CD 6277 0E5B 6867 C514 B85B 5D69