Build libgdal with libgeos support

According to https://www.pythonanywhere.com/forums/topic/2801/ this will
allow users of osgeo, geopandas, geodjango, and other related libraries
to operate without seeing a message like `ERROR 6: GEOS support not
enabled.` in their application logs.

builds/libraries/vendor/gdal

@@ -16,7 +16,7 @@ SOURCE_TARBALL="http://download.osgeo.org/gdal/${VERSION}/gdal-${VERSION}.tar.gz
 curl -L $SOURCE_TARBALL | tar zx
 
 pushd "gdal-${VERSION}"
-./configure --prefix=$OUT_PREFIX --enable-static=no  &&
+./configure --prefix=$OUT_PREFIX --enable-static=no --with-python --with-geos=yes &&
 make
 make install