Fixed gcc warning on script.c, getnpcid

git-svn-id: https://svn.code.sf.net/p/rathena/svn/trunk@15823 54d463be-8e91-2dee-dedb-b68131a5f0ec

src/map/script.c

@@ -6359,7 +6359,7 @@ BUILDIN_FUNC(getcharid)
 BUILDIN_FUNC(getnpcid)
 {
 	int num = script_getnum(st,2);
-	struct npc_data* nd;
+	struct npc_data* nd = NULL;
 
 	if( script_hasdata(st,3) )
 	{// unique npc name