[PR middle-end/117263] Avoid unused-but-set warning in genautomata

[PR middle-end/117263] Avoid unused-but-set warning in genautomata

This is a trivial bug where a user wanted to define NDEBUG when building
genautomata, presumably trying to debug its behavior.  This resulted in a
unused-but-set warning which caused the build to fail.

Dario included the trivial fixes in the PR which I put through the usual
bootstrap & regression test as well as compiling genautomata with NDEBUG.

Pushing to the trunk.

	PR middle-end/117263
gcc/
	* genautomata.cc (output_statistics): Avoid set but unnused warnings
	when compiling with NDEBUG.