primitives: fix ordering of LUMA_4x16 LUMA_16x4 to match other AMP partitions

This also fixes the testbench to properly represent 16x4 and 4x16 partition
primitives

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branch : stable
extra : source : 4db0aec57138647166fbc7dac5a3833376bb8cd6
encoder: prevent divide by zero in elapsedVideoTime calculation

--HG--
branch : stable
extra : source : 824ede6074a6d5550b6f716f999b88f9256f506b
rc: improvements for ABR

1. modify rateTolerance from 0.1 to 1.0, in order to allow the final bitrate to
fluctuate more(CBR to ABR)

2. ncu in initialization of ratecontrol is set according to 16x16 block size
which is same to x264, for the empirical formula in x264 is for 16x16 size.

3. do more modification to make ratecontrol algorithm of x265 more similar to
x264 for x264 has been developed for about 10 years and is very mature , it is
reasonale to take its method firstly.

--HG--
branch : stable
Added tag 0.5 for changeset 69acb3cb777f

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branch : stable