The first frame was always qp51 due to gop_offset being -1 for the
first frame. This fix makes it so that bits are allocated as if it was
the last (high quality) frame from the previous GOP.
The includes should make more sense now and not just happen to compile
due to headers included from other headers.
Used a modified version of IWYU. Modifications were to attribute int8_t
and so on to stdint.h instead of sys/types.h and immintrin.h instead of
more specific headers.
include-what-you-use 0.7 (git:b70df35)
based on clang version 3.9.0 (trunk 264728)
A 32 bit int overflowed after 2^31 bits (2Gb). It will still overflow
eventually, after 500 years of outputting 1Gb/s, but by that time,
I recon we will have fixed this properly and it's time to upgrade.
Some constants used in rate control are now initialized only once instead
of being computed on every frame. Adds pixels_per_pic, target_avg_bppic,
target_avg_bpp and gop_layer_weights to encoder_control_t.
