Add unit test for ref_frame_info

Fix several bugs to make the test pass.
1) Move update_frame_indexes() out of show_frame check.
2) Init coding_indexes[i] to -1 when key frame appears
3) Fix a bug in PostUpdateRefFrameInfo()

Change-Id: Ie7c70a1d460e5b89475a1aef77416fc9a88387e1
5 files changed