Many of the virProcess APIs are relying on GNULIB providing
POSIX API stubs. Even with these stubs the APIs don't do
anything useful once compiled. We can thus conditionalize
the code so that we don't compile anything at all.
Reviewed-by: NPavel Hrdina <phrdina@redhat.com>
Signed-off-by: NDaniel P. Berrangé <berrange@redhat.com>