fix for issue 51: _FILE_OFFSET_BITS misdefined
fix for issue 51: _FILE_OFFSET_BITS misdefined

--HG--
branch : dev-0.4

nlhepler/pysam,kyleabeauchamp/pysam,bioinformed/pysam,carolinux/pysam,TyberiusPrime/pysam,brendanofallon/pysam,kyleabeauchamp/pysam,kyleabeauchamp/pysam,mattions/pysam,mattions/pysam,nlhepler/pysam,nlhepler/pysam,carolinux/pysam,daler/pysam,carolinux/pysam,carolinux/pysam,dannon/pysam,pysam-developers/pysam,brendanofallon/pysam,daler/pysam,dannon/pysam,brendanofallon/pysam,mattions/pysam,bioinformed/pysam,TyberiusPrime/pysam,dannon/pysam,daler/pysam,bioinformed/pysam,mattions/pysam,dannon/pysam,carolinux/pysam,TyberiusPrime/pysam,brendanofallon/pysam,pysam-developers/pysam,TyberiusPrime/pysam,bioinformed/pysam,daler/pysam,brendanofallon/pysam,TyberiusPrime/pysam,nlhepler/pysam,mattions/pysam,dannon/pysam,nlhepler/pysam,pysam-developers/pysam,kyleabeauchamp/pysam,pysam-developers/pysam,bioinformed/pysam,daler/pysam,kyleabeauchamp/pysam