v.sample: use standardized options (https://trac.osgeo.org/grass/ticket/2409)

git-svn-id: https://svn.osgeo.org/grass/grass/trunk@63135 15284696-431f-4ddb-bdfa-cd5b030d7da7

vector/v.sample/main.c

@@ -99,7 +99,7 @@ int main(int argc, char **argv)
     parm.method->answer = "nearest";
 
     parm.z = G_define_option();
-    parm.z->key = "z";
+    parm.z->key = "zmultiplier";
     parm.z->type = TYPE_DOUBLE;
     parm.z->required = NO;
     parm.z->answer = "1.0";