Fix an issue in the shapefile GUI caused by saving the original shapefile name before...

Fix an issue in the shapefile GUI caused by saving the original shapefile name before processing.

This was a bug caused by having two separate passes during export; we were saving the original
export shapefile name during the first loop, and so when we came to free() the temporary name
at the end of export it would only free the shapefile name from the last iteration, and do it
multiple times causing random crashes.

git-svn-id: http://svn.osgeo.org/postgis/trunk@9030 b70326c6-7e19-0410-871a-916f4a2858ee