dosfstools: Update to 3.0.25.

Cleanup install process, with the following benefits:
* Now symlinks for fsck.msdos and fsck.vfat will be created.
* Manpages are shipped.
libusb: libusbx has been merged into libusb 1.0.18 again.
Merge remote-tracking branch 'stevee/dosfsutils-update'