no rdo: Turn OFF the early exit code

Turning off the early exit code since it increases the bitrate by 2%
This will be enabled when the hash mismatch issue is solved for the reuse of NxN
calculataion in early exit code
Tcombitstream: Encoded Bit stream storage (fifo) moved from std::vector to Non STL Class

1.Removed std::vector Class from Tcombitstream
2.Removed std::search_n algorithm from Tcombitstream
3.Implemented fifo using Pointers to an array  - Encoded Bit stream storage
primitives: add pixelavg primitive
Bidir ME: new logic adapted from x264

L0 and L1 MVs from unidir ME used for bidir MV. bidir cost is calculated from the average of references.
Bidir ME: add (0,0) candidate
api: remove dead bipredSearchRange parameter and CLI option
TEncSearch: remove methods unreachable after bidir replacement
replace sad_12 vector class function with intrinsic.
replace sad_24 vector class function with intrinsic.
replace sad_32 vector class function with intrinsic.
replace sad_x3_12 vector class function with intrinsic.
replace sad_x3_24 vector class function with intrinsic.
replace sad_x3_32 vector class function with intrinsic.
replace sad_x4_12 vector class function with intrinsic.
replace sad_x4_24 vector class function with intrinsic.
replace sad_x4_32 vector class function with intrinsic.
pixel: move avx2 functions into pixel-avx2.cpp
cmake: drop pixel-xop.cpp

Now that there are very few vector class intrinsics left, there is almost no
point to compiling pixel.inc with the XOP flag enabled.  This saves compile
time.  It's setup function wasn't even being called.
pixel: cleanup pixel.inc

Remove copy of C primitive transpose
Move 8bpp-only functions to pixel8.inc
cleanup setup function
cmake: move SSSE3 routines into pixel-ssse3.cpp