Fix unused warnings

http://ci.rvm.jp/results/trunk_gcc7@silicon-docker/2539622
```
/tmp/ruby/v2/src/trunk_gcc7/class.c: In function 'rb_scan_args_parse':
/tmp/ruby/v2/src/trunk_gcc7/class.c:1971:12: warning: unused variable 'tmp_buffer' [-Wunused-variable]
     VALUE *tmp_buffer = arg->tmp_buffer;
            ^~~~~~~~~~
```
```
In file included from /tmp/ruby/v2/src/trunk_gcc7/vm_insnhelper.c:1895:0,
                 from /tmp/ruby/v2/src/trunk_gcc7/vm.c:349:
/tmp/ruby/v2/src/trunk_gcc7/vm_args.c:212:1: warning: 'args_stored_kw_argv_to_hash' defined but not used [-Wunused-function]
 args_stored_kw_argv_to_hash(struct args_info *args)
 ^~~~~~~~~~~~~~~~~~~~~~~~~~~
```

1 files changed, 0 insertions, 23 deletions

diff --git a/vm_args.c b/vm_args.c
index 3558d6487f..5bed9711de 100644
--- a/vm_args.c
+++ b/vm_args.c
@@ -208,29 +208,6 @@ args_kw_argv_to_hash(struct args_info *args)
     return args->argc;
 }
 
-static void
-args_stored_kw_argv_to_hash(struct args_info *args)
-{
-    int i;
-    const struct rb_call_info_kw_arg *kw_arg = args->kw_arg;
-    const VALUE *const passed_keywords = kw_arg->keywords;
-    const int passed_keyword_len = kw_arg->keyword_len;
-    VALUE h = rb_hash_new_with_size(passed_keyword_len);
-
-    for (i=0; i<passed_keyword_len; i++) {
-	rb_hash_aset(h, passed_keywords[i], args->kw_argv[i]);
-    }
-    args->kw_argv = NULL;
-
-    if (args->rest) {
-	arg_rest_dup(args);
-	rb_ary_push(args->rest, h);
-    }
-    else {
-	args->argv[args->argc++] = h;
-    }
-}
-
 static inline void
 args_setup_lead_parameters(struct args_info *args, int argc, VALUE *locals)
 {