avr: Fix ICE on optimize attribute.

avr: Fix ICE on optimize attribute.

This commit fixes an ICE when an optimize attribute changes the prevailing
optimization level.

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105069 describes the
same ICE for the sh target, where the fix was to enable save/restore of
target specific options modified via TARGET_OPTIMIZATION_TABLE hook.

For the AVR target, mgas-isr-prologues and -mmain-is-OS_task are those
target specific options. As they enable generation of more optimal code,
this commit adds the Optimization option property to those option records,
and that fixes the ICE.

Regression run shows no regressions, and >100 new PASSes.

	PR target/110086

gcc/ChangeLog:

	* config/avr/avr.opt (mgas-isr-prologues, mmain-is-OS_task):
	Add Optimization option property.

gcc/testsuite/ChangeLog:

	* gcc.target/avr/pr110086.c: New test.