mport sample file handling can write outside the configured root

mport is the MidnightBSD Package Manager. Prior to 2.7.8, create_sample_file() in libmport/bundle_read_install_pkg.c did not constrain absolute source and destination paths from the sample-file manifest directive to mport->root. A malicious or malformed package manifest could therefore direct privileged sample-file handling to copy or write outside the configured installation root, compromising local filesystem integrity. This issue is fixed in version 2.7.8.