GTiff/internal libgeotiff: GTIFGetDefn(): deal with Polyconic and Equirectangular when reading PCS code only; import from EPSG equirectangular with EPSG method=9842, like EPSG:32663

git-svn-id: https://svn.osgeo.org/gdal/trunk/gdal@28241 f0d54148-0727-0410-94bb-9a71ac55c965