Weston crash when system comes back from sleep state.

1. Launch weston.
2. Let system go to sleep with no activity.
3. Once system goes to sleep with dark screen, move mouse to wake up the system.
4. when the system come back instead of weston screen it goes back to VT terminal reporting crash

The crash is coming from weston_output_finish_frame

assert(timespec_sub_to_nsec(stamp, &output->frame_time) >= 0);

Crash :

#0 __pthread_kill_implementation (no_tid=0, signo=6, threadid=123530462787776) at ./nptl/pthread_kill.c:44

#1 __pthread_kill_internal (signo=6, threadid=123530462787776) at ./nptl/pthread_kill.c:78

#2 __GI___pthread_kill (threadid=123530462787776, signo=signo@entry=6) at ./nptl/pthread_kill.c:89

#3 0x00007059ada42476 in __GI_raise (sig=sig@entry=6) at ../sysdeps/posix/raise.c:26

#4 0x00007059ada287f3 in __GI_abort () at ./stdlib/abort.c:79

#5 0x00007059ada2871b in __assert_fail_base (fmt=0x7059adbdd130 "%s%s%s:%u: %s%sAssertion `%s' failed.\n%n", assertion=0x7059add24c28 "timespec_sub_to_nsec(stamp, &output->frame_time) >= 0", file=0x7059add24545 "../libweston/compositor.c", line= 3273, function=<optimized out>) at ./assert/assert.c:92

#6 0x00007059ada39e96 in __GI___assert_fail (assertion=0x7059add24c28 "timespec_sub_to_nsec(stamp, &output->frame_time) >= 0", file=0x7059add24545 "../libweston/compositor.c", line=3273, function=0x7059add265a0 <__PRETTY_FUNCTION__.40> "weston_output_finish_frame") at ./assert/assert.c:101

#7 0x00007059adcf1151 in weston_output_finish_frame (output=0x650d28ae4bd0, stamp=0x7ffc5dbcd2a0,presented_flags=7) at ../libweston/compositor.c:3273

#8 0x00007059ad07d302 in drm_output_update_complete (output=0x650d28ae4bd0, flags=7, sec=0, usec=0) at ../libweston/backend-drm/drm.c:325

#9 0x00007059ad0899a3 in atomic_flip_handler (fd=14, frame=0, sec=0, usec=0, crtc_id=82, data=0x650d28ade050) at ../libweston/backend-drm/kms.c:1442

#10 0x00007059ad86651f in drmHandleEvent () at /lib/x86_64-linux-gnu/libdrm.so.2

#11 0x00007059ad089a4c in on_drm_input (fd=14, mask=1, data=0x650d28ade050) at ../libweston/backend-drm/kms.c:1458

timeout@entry=-1) at ../src/event-loop.c:1104 ```

``` #13 0x00007059adcada95 in wl_display_run (display=0x650d28ad12b0) at ../src/wayland-server.c:1493 ```

``` #14 0x00007059add722ed in wet_main (argc=1, argv=0x7ffc5dbce028, test_data=0x0) at ../compositor/main.c:3785 ```

``` #15 0x0000650d27600172 in main (argc=5, argv=0x7ffc5dbce028) at ../compositor/executable.c:33 ```