Fix diff.

Author: ioquatix

test/ruby/gdb.rb

@@ -51,7 +51,7 @@
 				puts "\nActual output:"
 				puts result[:output]
 				puts "\nDiff (line by line):"
-				result[:diff].each do |d|
+				result[:diff]&.each do |d|
 					puts "  Line #{d[:line]}:"
 					puts "    Expected: #{d[:expected].inspect}"
 					puts "    Actual:   #{d[:actual].inspect}"