change type of RString.size from size_t to long

include/mruby/string.h

@@ -26,7 +26,7 @@ extern const char ruby_digitmap[];
 
 struct RString {
   MRUBY_OBJECT_HEADER;
-  size_t len;
+  long len;
   union {
     size_t capa;
     mrb_value shared;

src/cdump.c

@@ -146,7 +146,7 @@ make_cdump_irep(mrb_state *mrb, int irep_no, FILE *f)
           }
         }
         memset(buf, 0, buf_len);
-        SOURCE_CODE("  irep->pool[%d] = mrb_str_new(mrb, \"%s\", %zd);",               n, str_to_format(irep->pool[n], buf), RSTRING_LEN(irep->pool[n])); break;
+        SOURCE_CODE("  irep->pool[%d] = mrb_str_new(mrb, \"%s\", %ld);",               n, str_to_format(irep->pool[n], buf), RSTRING_LEN(irep->pool[n])); break;
       /* TODO MRB_TT_REGEX */
       default: break;
       }