add missing close(waitQmp)
add missing close(waitQmp)

after vm shutdown, the goroutine was stalled on
qemu.(*QemuContext).Close(). fix it by adding missing close(waitQmp).

       0x9f47e4
github.com/hyperhq/hyperd/vendor/github.com/hyperhq/runv/hypervisor/qemu.(*QemuContext).Close+0x84
/root/work/gopath/src/github.com/hyperhq/hyperd/vendor/github.com/hyperhq/runv/hypervisor/qemu/qemu.go:181
       0x683650
github.com/hyperhq/hyperd/vendor/github.com/hyperhq/runv/hypervisor.(*VmContext).Close+0x130
/root/work/gopath/src/github.com/hyperhq/hyperd/vendor/github.com/hyperhq/runv/hypervisor/context.go:224
       0x695e93
github.com/hyperhq/hyperd/vendor/github.com/hyperhq/runv/hypervisor.stateRunning+0x1b3
/root/work/gopath/src/github.com/hyperhq/hyperd/vendor/github.com/hyperhq/runv/hypervisor/vm_states.go:227
       0x68819e
github.com/hyperhq/hyperd/vendor/github.com/hyperhq/runv/hypervisor.(*VmContext).loop+0x29e
/root/work/gopath/src/github.com/hyperhq/hyperd/vendor/github.com/hyperhq/runv/hypervisor/hypervisor.go:24

Signed-off-by: Lai Jiangshan <b337eedf453972390e4695e362aeea2634ef4e0c@gmail.com>

hyperhq/runv,gao-feng/runv,jinfenw/runv,feiskyer/runv,jinfenw/runv,gao-feng/runv,bergwolf/runv,hyperhq/runv,hyperhq/runv,laijs/runv,laijs/runv,gnawux/runv,gnawux/runv,feiskyer/runv,laijs/runv,bergwolf/runv,bergwolf/runv,gnawux/runv,gao-feng/runv,jinfenw/runv