Segfault in afptool, if path in "package-file" is longer or equal to 60 characters

[Angus71]

While using the afptool with a "package-file", which has a path longer or equal to 60 characters (Which might occur, if used in a yocto build environment) a segmentation fault might occur.

I tried to fix it with Angus71/rockchip-mkbootimg@6a9341e, I've tested it and it worked okay for me, but further testing might be useful.