qemu: add QEMU_CAPS_MACHINE_VMPORT_OPT

Set the capability based on qmp query, or qemu version.  The qmp query
includes vmport with 2.2, but no longer with 2.3. It lists only
non-machine specific capabilities, so check the qemu version too until a
machine-specific query is supported.

src/qemu/qemu_capabilities.c

@@ -279,6 +279,8 @@ VIR_ENUM_IMPL(virQEMUCaps, QEMU_CAPS_LAST,
               "qxl.vgamem_mb",
               "qxl-vga.vgamem_mb",
               "pc-dimm",
+
+              "machine-vmport-opt", /* 185 */
     );
 
 
@@ -2509,6 +2511,7 @@ struct virQEMUCapsCommandLineProps {
 
 static struct virQEMUCapsCommandLineProps virQEMUCapsCommandLine[] = {
     { "machine", "mem-merge", QEMU_CAPS_MEM_MERGE },
+    { "machine", "vmport", QEMU_CAPS_MACHINE_VMPORT_OPT },
     { "drive", "discard", QEMU_CAPS_DRIVE_DISCARD },
     { "realtime", "mlock", QEMU_CAPS_MLOCK },
     { "boot-opts", "strict", QEMU_CAPS_BOOT_STRICT },
@@ -3255,6 +3258,10 @@ virQEMUCapsInitQMPMonitor(virQEMUCapsPtr qemuCaps,
     if (qemuCaps->version >= 1006000)
         virQEMUCapsSet(qemuCaps, QEMU_CAPS_DEVICE_VIDEO_PRIMARY);
 
+    /* vmport option is supported v2.2.0 onwards */
+    if (qemuCaps->version >= 2002000)
+        virQEMUCapsSet(qemuCaps, QEMU_CAPS_MACHINE_VMPORT_OPT);
+
     if (virQEMUCapsProbeQMPCommands(qemuCaps, mon) < 0)
         goto cleanup;
     if (virQEMUCapsProbeQMPEvents(qemuCaps, mon) < 0)

src/qemu/qemu_capabilities.h

@@ -224,6 +224,7 @@ typedef enum {
     QEMU_CAPS_QXL_VGAMEM         = 182, /* -device qxl.vgamem_mb */
     QEMU_CAPS_QXL_VGA_VGAMEM     = 183, /* -device qxl-vga.vgamem_mb */
     QEMU_CAPS_DEVICE_PC_DIMM     = 184, /* pc-dimm device */
+    QEMU_CAPS_MACHINE_VMPORT_OPT = 185, /* -machine xxx,vmport=on/off/auto */
 
     QEMU_CAPS_LAST,                   /* this must always be the last item */
 } virQEMUCapsFlags;