remote: remove some __sun conditionals

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>