* opts.h: Include obstack.h.
(opts_concat): New prototype.
(opts_obstack): New declaration.
* opts.c (opts_concat): New function.
(opts_obstack): New variable.
(init_options_struct): Call gcc_init_obstack on opts_obstack.
(finish_options): Use opts_concat instead of concat
and XOBNEWVEC instead of XNEWVEC.
* opts-common.c (generate_canonical_option, decode_cmdline_option,
generate_option): Likewise.
* Makefile.in (OPTS_H): Depend on $(OBSTACK_H).
* lto-wrapper.c (main): Call gcc_init_obstack on opts_obstack.