FindGDAL uses GDAL's 'gdal-config' utility to obtain the path to GDAL's library
(on systems identified by CMake's UNIX variable). Older versions formatted this
information like that of dependent libraries:
  -L/path/to/gdal/lib -lgdal[suffix]

Newer versions instead provide the full path to the library:
  /path/to/gdal/lib/[prefix]gdal[suffix]

FindGDAL now supports both formats. Entries that don't start with '-L' or '-l'
are only considered if they are absolute paths that exist on disk.
Furthermore, libraries are only considered if the name contains 'gdal'
(checked case-insensitively).