Fix distcheck run under CI.

check_gpx.sh now uses test_file_load program, so needs a DISPLAY to work with GTK3

test/Makefile.am

@@ -18,7 +18,6 @@ TESTS = check_degrees_conversions.sh \
 	check_parse_latlon.sh \
 	check_babel.sh \
 	check_vikgoto.sh \
-	check_gpx.sh \
 	check_geojson_osrm.sh \
 	check_help_xml.sh \
 	check_metatile.sh
@@ -32,6 +31,7 @@ endif
 #  which essentially means needs a display to work. Thus under some CI circumstances there is no DISPLAY,
 #  so ATM simplest to avoid/skip the following tests
 if HAVEDISPLAY
+TESTS += check_gpx.sh
 TESTS += check_fit.sh
 TESTS += check_kml.sh
 TESTS += check_tcx.sh