try to automatically detect GEOS lib location (instead of forcing user to set GEOS_DIR env var). On Leopard, env vars don't get passed by sudo.
try to automatically detect GEOS lib location (instead of forcing user
to set GEOS_DIR env var). On Leopard, env vars don't get passed by
sudo.

svn path=/trunk/toolkits/basemap/; revision=4672

matplotlib/basemap,guziy/basemap,matplotlib/basemap,guziy/basemap