DO NOT MERGE Fixed bug in the case of resolution change.

Modified the way i4_header_decoded in decoder context
is used, to ensure that resolution change is detected
even if PPS has not been decoded.

Bug: 35583675
Test: ran POC, no longer hangs

Change-Id: Ibb3f8dfbeb66a999fd81720a7d2a02dd951a55c4
(cherry picked from commit 1d06027c69e31d450b1e837c81073362d41084d3)