Remove dependency of this function on asm_offsets. ssse3/sse4 next.
Change quant_shift calculation so it be done using SIMD. Pre-calculate
as much as possible to simplify EOB selection.
Take advantage of qcoeff being zero'd by tying the if statements
together.
Speed parity with previous implementation with gcc x86_64 linux
Change-Id: Ife97556a1eca3a74b09def1a3d04084974dff1fb
Reduce dependency on offsets file by using intrinsics. Disassembly shows
improvements over previous assembly specifically in register management,
preloading, and {pro,epi}log. Speed change is within margin of error.
Change-Id: I8131b4b4d62bc092407fe847bfaa8f2c0e1384ff