ogsf: fix exag guess

git-svn-id: https://svn.osgeo.org/grass/grass/trunk@56496 15284696-431f-4ddb-bdfa-cd5b030d7da7

lib/ogsf/GS2.c

@@ -2314,6 +2314,7 @@ int GS_get_exag_guess(int id, float *exag)
 
     /* if gs is type const return guess = 1.0 */
     if (CONST_ATT == gs_get_att_src(gs, ATT_TOPO)) {
+	*exag = guess;
 	return (1);
     }