Fix require_relative to load files from non-ASCII paths

Closes oneclick/rubyinstaller2#265

Author: larskanis

localeinit.c

@@ -47,8 +47,7 @@ locale_charmap(VALUE (*conv)(const char *))
 # endif
     if (!codeset) {
         UINT codepage = ruby_w32_codepage[0];
-        if (!codepage) codepage = GetConsoleCP();
-        if (!codepage) codepage = GetACP();
+        if (!codepage) codepage = CP_UTF8;
         CP_FORMAT(cp, codepage);
         codeset = cp;
     }

ruby.c

@@ -1982,7 +1982,11 @@ process_options(int argc, char **argv, ruby_cmdline_options_t *opt)
     ruby_init_loadpath();
 
     Init_enc();
+#ifdef _WIN32
+    lenc = rb_utf8_encoding();
+#else
     lenc = rb_locale_encoding();
+#endif
     rb_enc_associate(rb_progname, lenc);
     rb_obj_freeze(rb_progname);
     parser = rb_parser_new();