Fails to build from source with multiarched python3.3 on Debian-like systems

On debian and ubuntu, python3.3 has two include locations instead of one:

-I/usr/include/<multiarch>/python3.3 -I/usr/include/python3.3

are needed.

Here is patch against postgresql 9.1 to fix fail to build from source
against such pythons.

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Regards,
Dmitrijs.