The c code implementation of 32x32 quantization does the zbin check
of all coefficients prior to the quant/dequant loop, hence removing
the redundant zbin check inside the loop. This only affects the
c code version. SSSE3 version does not separate the zbin check out.

Change-Id: Ic197a7d61d0b25fcac3cc092987651378cb56e4e