hook/table.c: Populate links from first match

The loaded module list is kept in the order the modules are first
loaded. Using the first loaded module (i.e. the EXE) will help
ensure that multiple hook DLLs stack correctly. Previously the link
was taken from the most-recently loaded module.

hook/table.c

@@ -93,7 +93,7 @@ static void hook_table_apply_to_iid(
             sym = &syms[j];
 
             if (hook_table_match_proc(&iate, sym)) {
-                if (sym->link != NULL) {
+                if (sym->link != NULL && *sym->link == NULL) {
                     *sym->link = *iate.ppointer;
                 }