opts: fix -gtoggle + optimize attribute

Note -fvar-tracking is enabled automatically with OPT_LEVELS_1_PLUS and
so we need to drop it if we are called from optimize attribute and the
option is unset.

	PR middle-end/104381

gcc/ChangeLog:

	* opts.cc (finish_options): If debug info is disabled
	(debug_info_level) and -fvar-tracking is unset, disable it.

gcc/testsuite/ChangeLog:

	* gcc.dg/pr104381.c: New test.