iris: return a dummy fence for a signaled fd
When an application calls create_fence_fd to get a fence for a signaled fd, instead of returning NULL, this patch creates a fence with a dummy syncobj.
The problem can be reproduced with weston-simple-dmabuf-egl, the application crashes to console with the following error message:
weston-simple-dmabuf-egl: ../weston-6.0.0/clients/simple-dmabuf-egl.c:907: wait_for_buffer_release_fence: Assertion `sync' failed. Aborted
Fixes: a3a73d11 "iris: Print warning and return *out = NULL when fd to syncobj fails" Signed-off-by: James Xiong james.xiong@intel.com