Consider invalid present fence time in FrameTimeline

Virtual devices could send the present fence signal time as
SIGNAL_TIME_INVALID (-1) due to the present fence is unreliable
property. The current behavior silently drops the DisplayFrame along
with its SurfaceFrames. These SurfaceFrames could have been added to
pending jank list which require the present time to be set.

Aside from virtual devices, there also seems to be a very rare
occurrence of invalid signal time in physical devices. The repro rate is
very very low but happens around phone locking and unlocking after a
large interval. This could be tied to lifecycle of fences but its better
we address invalid signal times to solve this too.

Bug: 182006762
Test: libsurfaceflinger_unittest
Change-Id: I3a501dd070e86a2cd719a9251c22ab9cba38c16b