libgis: report none color also for G_OPT_C_FG

        (merge https://trac.osgeo.org/grass/changeset/62946 from trunk)


git-svn-id: https://svn.osgeo.org/grass/grass/branches/releasebranch_7_0@62948 15284696-431f-4ddb-bdfa-cd5b030d7da7

lib/gis/parser_standard_options.c

@@ -579,7 +579,8 @@ struct Option *G_define_standard_option(int opt)
 	Opt->answer = DEFAULT_FG_COLOR;
 	Opt->gisprompt = "old,color,color";
 	Opt->label = _("Color");
-	Opt->description = _("Either a standard color name or R:G:B triplet");
+	Opt->description =
+	    _("Either a standard color name, R:G:B triplet, or \"none\"");
 	break;
     case G_OPT_C_BG:
 	Opt->key = "bgcolor";