Revert "autotest.sh to cat *.err on error"

This reverts commit 21fa8972f3.

tests/tools/autotest.sh

@@ -226,7 +226,6 @@ do
 		if $warn_iverilog_git; then
 			echo "Note: Make sure that 'iverilog' is an up-to-date git checkout of Icarus Verilog."
 		fi
-		cat ${bn}.err
 		$keeprunning || exit 1
 	fi
 done