Set io_layout to "1,1" when not C768

- retain io_layout="4,4" when C768
- add io_layout="1,1" when not C768, lower resolution layouts not always divisible by 4
- brings in matching change in config.fcst from develop branch

Refs: #363

parm/config/config.fcst

@@ -250,7 +250,11 @@ elif [[ "$CDUMP" == "gfs" ]] ; then # GFS cycle specific parameters
     export adjust_dry_mass=".false."
 
     # Write each restart file in 16 small files to save time
-    export io_layout="4,4"
+    if [ $CASE = C768 ]; then
+      export io_layout="4,4"
+    else
+      export io_layout="1,1"
+    fi
 
 
 fi