use G_OPT_M_NULL_VALUE

git-svn-id: https://svn.osgeo.org/grass/grass/branches/releasebranch_7_0@63016 15284696-431f-4ddb-bdfa-cd5b030d7da7

db/db.select/main.c

@@ -232,11 +232,7 @@ void parse_command_line(int argc, char **argv)
     vs->answer = NULL;
     vs->guisection = _("Format");
 
-    nv = G_define_option();
-    nv->key = "nv";
-    nv->type = TYPE_STRING;
-    nv->required = NO;
-    nv->description = _("Null value indicator");
+    nv = G_define_standard_option(G_OPT_M_NULL_VALUE);
     nv->guisection = _("Format");
 
     output = G_define_standard_option(G_OPT_F_OUTPUT); 

raster/r.describe/main.c

@@ -59,13 +59,8 @@ int main(int argc, char *argv[])
     /* define different options */
     option.map = G_define_standard_option(G_OPT_R_MAP);
 
-    option.nv = G_define_option();
-    option.nv->key = "nv";
-    option.nv->type = TYPE_STRING;
-    option.nv->required = NO;
-    option.nv->multiple = NO;
+    option.nv = G_define_standard_option(G_OPT_M_NULL_VALUE);
     option.nv->answer = "*";
-    option.nv->description = _("String representing no data cell value");
 
     option.nsteps = G_define_option();
     option.nsteps->key = "nsteps";