Details:
- Updated s and d microkernels in bli_gemm_asm_d8x6.c to relax alignment
constraints.
- Added missing c and z microkernels, which are based on the corresponding
kernels in the d6x8 set.
- This completes the d8x6 set (which may be used for situations when it
is desirable to have a microkernel with a column preference).
8a11a2174a