Fix compilation error on Windows.
Fix compilation error on Windows.

tanmengwen/libmv,Shinohara-Takayuki/libmv,hjm168168/libmv,sanyaade-g2g-repos/libmv,manjunathnarayana/libmv,leoujz/libmv,pombreda/libmv,KangKyungSoo/libmv,Shinohara-Takayuki/libmv,pombreda/libmv,manjunathnarayana/libmv,Ashwinning/libmv,pombreda/libmv,tanmengwen/libmv,hjm168168/libmv,Danath/libmv,manjunathnarayana/libmv,Danath/libmv,tanmengwen/libmv,Danath/libmv,sanyaade-g2g-repos/libmv,leoujz/libmv,leoujz/libmv,guivi01/libmv,jackyspeed/libmv,Danath/libmv,hjm168168/libmv,sanyaade-g2g-repos/libmv,Ashwinning/libmv,sanyaade-g2g-repos/libmv,jackyspeed/libmv,Ashwinning/libmv,KangKyungSoo/libmv,tanmengwen/libmv,guivi01/libmv,KangKyungSoo/libmv,guivi01/libmv,jackyspeed/libmv,Ashwinning/libmv,guivi01/libmv,leoujz/libmv,KangKyungSoo/libmv,jackyspeed/libmv,Shinohara-Takayuki/libmv,pombreda/libmv,manjunathnarayana/libmv,Shinohara-Takayuki/libmv,hjm168168/libmv