stubs: move vhost stubs to stubs/vhost.o

No need to include them in libqemustub.a, since only system emulators
need them.
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

hw/Makefile.objs

@@ -29,7 +29,7 @@ devices-dirs-$(CONFIG_SOFTMMU) += timer/
 devices-dirs-$(CONFIG_TPM) += tpm/
 devices-dirs-$(CONFIG_SOFTMMU) += usb/
 devices-dirs-$(CONFIG_SOFTMMU) += vfio/
-devices-dirs-$(CONFIG_VIRTIO) += virtio/
+devices-dirs-$(CONFIG_SOFTMMU) += virtio/
 devices-dirs-$(CONFIG_SOFTMMU) += watchdog/
 devices-dirs-$(CONFIG_SOFTMMU) += xen/
 devices-dirs-$(CONFIG_MEM_HOTPLUG) += mem/

hw/virtio/Makefile.objs

+ifeq ($(CONFIG_VIRTIO),y)
 common-obj-y += virtio-rng.o
 common-obj-$(CONFIG_VIRTIO_PCI) += virtio-pci.o
 common-obj-y += virtio-bus.o
@@ -5,7 +6,10 @@ common-obj-y += virtio-mmio.o
 
 obj-y += virtio.o virtio-balloon.o 
 obj-$(CONFIG_LINUX) += vhost.o vhost-backend.o vhost-user.o
-
 obj-$(CONFIG_VHOST_VSOCK) += vhost-vsock.o
 obj-y += virtio-crypto.o
 obj-$(CONFIG_VIRTIO_PCI) += virtio-crypto-pci.o
+endif
+
+common-obj-$(call lnot,$(CONFIG_LINUX)) += vhost-stub.o
+common-obj-$(CONFIG_ALL) += vhost-stub.o

stubs/Makefile.objs

@@ -35,7 +35,6 @@ stub-obj-y += kvm.o
 stub-obj-y += qmp_pc_dimm_device_list.o
 stub-obj-y += target-monitor-defs.o
 stub-obj-y += target-get-monitor-def.o
-stub-obj-y += vhost.o
 stub-obj-y += iohandler.o
 stub-obj-y += pc_madt_cpu_entry.o
 stub-obj-y += migration-colo.o