g.proj: do not require -t flag when datumtrans=-1 given (keep consistency with grass70)

git-svn-id: https://svn.osgeo.org/grass/grass/trunk@68203 15284696-431f-4ddb-bdfa-cd5b030d7da7

general/g.proj/datumtrans.c

@@ -130,8 +130,10 @@ int set_datumtrans(int datumtrans, int force)
 	    G_debug(3, "set_datumtrans(): datum transform terms found "
 		    "with %d options", paramsets);
 
-	    if (status == 1 && paramsets > 1)
-		/* Parameters are missing and there is a choice to be made */
+	    if (paramsets > 1 && (status == 1 || datumtrans == -1))
+		/* Parameters are missing and there is a choice to be
+                   made / or / user asked to print datum
+                   transformation parameters */
 		force = 1;
 
 	}