Bug#1016688: Acknowledgement (dieharder -h segfaults)

[Milan Broz]

Actually this patch is better, just displays usage and also check upper 
boundary (another segault with -d 100000 ...)

https://github.com/mbroz/dieharder/commit/7d60208c8a8beabe6d3d5a88399b83ebf03240a5