Missing config file message breaks compatibility with gpg-agent

[ashiire]

Hi,

I've run into problems with a debug message regarding default config; apparently it is directed to stdout, where gpg-agent takes offense and refuses to acknowledge the program as pinentry :C

https://github.com/ritze/pinentry-dmenu/blob/a77bb7a194060b4174bb51e9ad9619c9d9d0a787/pinentry-dmenu.c#L788

The below message might also be intended to go to stderr? I'm not that sure.

https://github.com/ritze/pinentry-dmenu/blob/a77bb7a194060b4174bb51e9ad9619c9d9d0a787/pinentry-dmenu.c#L167

Thanks for your efforts, btw, it's a neat tool!