Fix gettext reload bugs (e.g. inability to disable gettext

once enabled).

	* grub-core/gettext/gettext.c: Encapsulate all static variables in
	main_context and secondary_context. All functions updated.
	(grub_gettext_translate): Rename to ...
	(grub_gettext_translate_real): ... this. Return NULL on failed
	translate.
	(grub_gettext_translate): Handle secondary context.
	(grub_gettext_delete_list): Close file and zero-out the context.
	(grub_mofile_open): Don't call grub_gettext_delete_list.
	Don't close file.
	(grub_gettext_init_ext): Call grub_gettext_init_ext. Skip loading
	if locale="" to avoid pointless error message.
	(grub_gettext_env_write_lang): Update lang even if load fails.
	Handle secondary context.
	(grub_gettext_reread_prefix): New function.
	(read_main): Likewise.
	(read_secondary): Likewise.
	(GRUB_MOD_INIT): Handle secondary context. Hook and export variables.
	(GRUB_MOD_FINI): Handle secondary context. Don't close file.
	* grub-core/normal/main.c (read_lists): Call grub_gettext_reread_prefix.
	* include/grub/normal.h (grub_gettext_reread_prefix): New proto.

grub-core/normal/main.c

@@ -269,6 +269,7 @@ read_lists (const char *val)
       read_crypto_list (val);
       read_terminal_list (val);
     }
+  grub_gettext_reread_prefix (val);
 }
 
 static char *