Added in QEMU commit of v3.0.0-rc0~48^2~9 (then fixed by
v3.1.0-rc0~119^2~37) QEMU is replacing '-realtime mlock' with
'-overcommit mem-lock'. Add a capability to tell if we're dealing
new new enough qemu to use the replacement.
Signed-off-by: NMichal Privoznik <mprivozn@redhat.com>
Reviewed-by: NJán Tomko <jtomko@redhat.com>