Most devices don’t need to open many fds. However, an implementation detail of minijail is that
after applying this limit, it opens an additional file descriptor to scan the /proc/self/fd
directory to choose which file descriptors to close in the child process. The open files limit
therefore has to be higher than the number file descriptors that the parent thread holds open
before the jail is started.
Creates a [Minijail] instance which just invokes a jail process and sets
max_open_files using RLIMIT_NOFILE. This is helpful with crosvm process
runs as a non-root user without SYS_ADMIN capabilities.