fallback_build_mingw32_under_unix.sh: add support for x86_64-w64-mingw32

git-svn-id: https://svn.osgeo.org/gdal/trunk@27147 f0d54148-0727-0410-94bb-9a71ac55c965
Add python bindings
Merge branch 'trunk' into trunk_mingw_w64