Adding support for Mercator_Auxilary_Sphere without AUTHORITY SECTIONS.
Fixes issue #3962


git-svn-id: https://svn.osgeo.org/gdal/trunk@27594 f0d54148-0727-0410-94bb-9a71ac55c965
Testing the fix for issue #3962.


git-svn-id: https://svn.osgeo.org/gdal/trunk@27595 f0d54148-0727-0410-94bb-9a71ac55c965