vn_open(9) does not pass the open(2) flags to VOP_CREATE(9) so we can't

vn_open(9) does not pass the open(2) flags to VOP_CREATE(9) so we can't
support FBT_CREATE. Fall back to FBT_MKNOD + FBT_OPEN so that a valid
sequence of FUSE messages is sent to the file system when creating files.

input from mpi@, otto@