HFA: fix recognition of Hotine Mercator Azimuth Center in Imagine format (and Swisstopo GeoTIFF) (#5551)

git-svn-id: https://svn.osgeo.org/gdal/trunk@27480 f0d54148-0727-0410-94bb-9a71ac55c965
Merge branch 'trunk' into trunk_travis_macosx