GMT 5.4.0 does not compile without GDAL
|Target version:||Candidate for next bugfix release|
grdimage.c and gmt_io.c both require the element gdal_read_in in GMT→current, which does not exist if GDAL is not used.
Hence, it this case GMT does not compile.
This affects GMT 5.4.0 (and likely the trunk version as well).