* opts.h (cl_option_state): New structure.
(get_option_state): Declare.
* opts.c (get_option_state): New function.
* toplev.c (option_affects_pch_p): New function.
(default_get_pch_validity): Store the state of all options for which
option_affects_pch_p returns true.
(default_pch_valid_p): Check the state of those options here.
Only check target_flags separately if targetm.check_pch_target_Flags
is nonnull or if TARGET_SWITCHES is defined.
From-SVN: r100430
