mjit.c: rb_w32_system_tmpdir is not in headers

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@62323 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

mjit.c

@@ -1199,6 +1199,10 @@ valid_class_serials_add_i(ID key, VALUE v, void *unused)
     return ID_TABLE_CONTINUE;
 }
 
+#ifdef _WIN32
+UINT rb_w32_system_tmpdir(WCHAR *path, UINT len);
+#endif
+
 static char *
 system_tmpdir(void)
 {