Use new specifiers/modifiers of `mrb_vfromat()`

The binary sizes (gems are only `mruby-bin-mruby`) are reduced slightly in
my environment than before the introduction of new specifiers/modifiers
(5116789a) with this change.

  ------------+-------------------+-------------------+--------
   BINARY     | BEFORE (5116789a) |   AFTER (This PR) |  RATIO
  ------------+-------------------+-------------------+--------
   mruby      |      593416 bytes |      593208 bytes | -0.04%
   libmruby.a |      769048 bytes |      767264 bytes | -0.23%
  ------------+-------------------+-------------------+--------

BTW, I accidentally changed `tasks/toolchains/visualcpp.rake` at #4613,
so I put it back.

1 files changed, 7 insertions, 7 deletions

diff --git a/mrbgems/mruby-eval/src/eval.c b/mrbgems/mruby-eval/src/eval.c
index 30534aaec..e8f1d3e95 100644
--- a/mrbgems/mruby-eval/src/eval.c
+++ b/mrbgems/mruby-eval/src/eval.c
@@ -254,15 +254,15 @@ create_proc_from_string(mrb_state *mrb, char *s, mrb_int len, mrb_value binding,
     mrb_value str;
 
     if (file) {
-      str = mrb_format(mrb, " file %S line %S: %S",
-                       mrb_str_new_cstr(mrb, file),
-                       mrb_fixnum_value(p->error_buffer[0].lineno),
-                       mrb_str_new_cstr(mrb, p->error_buffer[0].message));
+      str = mrb_format(mrb, "file %s line %d: %s",
+                       file,
+                       p->error_buffer[0].lineno,
+                       p->error_buffer[0].message);
     }
     else {
-      str = mrb_format(mrb, " line %S: %S",
-                       mrb_fixnum_value(p->error_buffer[0].lineno),
-                       mrb_str_new_cstr(mrb, p->error_buffer[0].message));
+      str = mrb_format(mrb, "line %d: %s",
+                       p->error_buffer[0].lineno,
+                       p->error_buffer[0].message);
     }
     mrb_parser_free(p);
     mrbc_context_free(mrb, cxt);