mp4decrypt file path length limit

[Jaynator495]

There appears to be a file path length limit before the program just errors out. From testing, the limit appears to be 254 characters long (excluding /'s for directories), 255 and greater will error out. I assume it's somehow an 8 bit limit. Would it be possible to fix this?

Additionally, I also noticed that if the filename includes unicode, it will also fail.