FindGDAL: Handle gdal-config printing absolute path to library
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).