libuuid: When starting uuidd, use waitpid() to reap the zombie process

libuuid: When starting uuidd, use waitpid() to reap the zombie process

The uuidd process will fork and let the parent process exit to create
the daemon.  So use waitpid to reap the zombie, as well as using it to
time when it is safe to try to connect to the daemon.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>