PR target/54816 is now fixed on mainline.  This adds a test case to
check that it doesn't regress in future.  Tested with a cross compiler
to avr-elf.  Committed as obvious.


2023-04-16  Roger Sayle  <roger@nextmovesoftware.com>

gcc/testsuite/ChangeLog
	PR target/54816
	* gcc.target/avr/pr54816.c: New test case.