vp9-rtc: Fixes to resizer for real-time

Reduce the time before sampling begins (after key)
and reduce averaging window, to make resize act
faster.

Reset RC paramaters for temporal layers on resize.

Add per-frame-bandwidth thresholds to force
downsize for extreme case, for HD input.

Change-Id: I8e08580b2216a2e6981502552025370703cd206c
2 files changed