[Bug] '--as' is not read when stdin is not the terminal

[nkakouros]

For instance, this:

printf | ssh-keydgen -t rsa --as 1 -f /tmp/qqq

fails, while:

ssh-keydgen -t rsa --as 1 -f /tmp/qqqqq

works.

[cornfeedhobo]

Thanks for reporting this. Unfortunately I'm not going to support this tool any further until I can re-evaluate a better scheme. The current approach is not future proof and is tightly coupled to the way golang is consuming the provided "entropy". However, pull requests are welcome.