Please give back mapnik on mipsel s390

[Jérémy Lal <kapouer@melix.org>]

Hello,

mapnik built successfully except on those two arches, for
no clear reason (out of memory on s390, hanged on mipsel).
I'd like to see if it's going to fail again before trying
to debug.

  gb mapnik_2.2.0+ds1-2 . mipsel s390

Thanks.

Jérémy.