getloadavg is supported on Linux, BSDs, Solaris.
Following man page:
RETURN VALUE
If the load average was unobtainable, -1 is returned; otherwise,
the number of samples actually retrieved is returned.
accordingly, make stub for systems which don't support this function return -1
for consistency.
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
dc864d3a37