opts.cc Simplify handling of explicit -flto-partition= and -fipa-reorder-for-locality

opts.cc Simplify handling of explicit -flto-partition= and -fipa-reorder-for-locality

The handling of an explicit -flto-partition= and -fipa-reorder-for-locality
should be simpler.  No need to have a new default option.  We can use opts_set
to check if -flto-partition is explicitly set and use that information in the
error handling.
Remove -flto-partition=default and update accordingly.

Bootstrapped and tested on aarch64-none-linux-gnu.

Signed-off-by: Kyrylo Tkachov <ktkachov@nvidia.com>
gcc/

	* common.opt (LTO_PARTITION_DEFAULT): Delete.
	(flto-partition=): Change default back to balanced.
	* flag-types.h (lto_partition_model): Remove LTO_PARTITION_DEFAULT.
	* opts.cc (validate_ipa_reorder_locality_lto_partition):
	Check opts_set->x_flag_lto_partition instead of LTO_PARTITION_DEFAULT.
	(finish_options): Remove handling of LTO_PARTITION_DEFAULT.

gcc/testsuite/

	* gcc.dg/completion-2.c: Remove check for default.

(cherry picked from commit 040f94d1f63c3607a2f3faf5c329c3b2b6bf7d1e)