hw/9pfs: handle undefined FS_IOC_GETVERSION case in handle_ioc_getversion()

All get_st_gen() implementations except handle_ioc_getversion() have
guard for undefined FS_IOC_GETVERSION. Let's add it there too.
Signed-off-by: NKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: NAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>

hw/9pfs/virtio-9p-handle.c

@@ -582,6 +582,7 @@ static int handle_unlinkat(FsContext *ctx, V9fsPath *dir,
 static int handle_ioc_getversion(FsContext *ctx, V9fsPath *path,
                                  mode_t st_mode, uint64_t *st_gen)
 {
+#ifdef FS_IOC_GETVERSION
     int err;
     V9fsFidOpenState fid_open;
 
@@ -599,6 +600,10 @@ static int handle_ioc_getversion(FsContext *ctx, V9fsPath *path,
     err = ioctl(fid_open.fd, FS_IOC_GETVERSION, st_gen);
     handle_close(ctx, &fid_open);
     return err;
+#else
+    errno = ENOTTY;
+    return -1;
+#endif
 }
 
 static int handle_init(FsContext *ctx)