libvpx

Fix bug in reference frame counting.

vp8_encode_inter_macroblock() is called in both pick_mb_modes() as
well as encode_sb(), thus the number of macroblocks in the counter
were twice as big as actual numbers. This doesn't affect output.

Change-Id: I6de8a996ee44d2f7f2080d8d2177dd7bc6207c93