Decoder: Fixed overflow in refernce list creation.

Since the maximum value of long term index is 255,
the loop control variable needs to be 32 bit.

Bug: 38448381
Test: ran POC before/after applying fix
Change-Id: Iae3ecff38d4a922bde10fde33f1cfcafd2ea2680
(cherry picked from commit cbcd2846fa837e4be6d35f5c1211b070bc8d26da)
2 files changed