Fix build as root.

Fix build as root.

As noted by Gerrit Renker, when trying to extract help text from
./para_audiod, the build stops when logged in as root because
para_audiod refuses to start as root if --user and --group are
not given.

This patch moves the check for UID==0 after the check for --help and
--detailed-help so that the help text may be extracted as root even
if no --user and --group options are given.