remote: remove some __sun conditionals
    
    The libvirtd daemon has some arbitrary logic to drop privileges, but
    only on Solaris platforms. This was added during Xen days, when Xen was
    the only driver running in libvirtd. There's no expectation or testing
    that this works with the new libxl stack, nor whether dropping
    privileges breaks any of the secondary drivers. Finally, we'll be
    splitting drivers out into their own independant daemons, so this won't
    be applicable to libvirtd in future anyway.
    
    The remote driver client meanwhile arbitrarily disables daemon
    auto-spawn when connecting as non-root, breaking a key feature of
    libvirt unprivileged connections.
    
    Since we've not had any contributions for Solaris since circa 2012
    and we don't do any CI testing we should consider this platform
    unmaintained and thus reasonable to remove this cruft. If someone steps
    forward to maintain Solaris again, this code would need re-evaluating to
    come up with something more targetted.
    
    There's various __sun conditionals in the Xen driver code, but those are
    not touched. This is all for the legacy Xen driver, which will be
    entirely removed at some point in future, so not benefit to hacking out
    just the Solaris parts.
    
    Reviewed-by: Andrea Bolognani <abologna@redhat.com>
    Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>