Crash in x264_quant_8x8_avx2

[lu-zero]

Disabling the assembly makes the encoding work OK.

lldb -- ./avconv -filter_complex testsrc -s hd720 -c:v libx262 /tmp/out.mpeg using this branch.

Process 62191 stopped
* thread #2: tid = 0xc3f87, 0x00000001011b6fa0 libx264.142.dylib`x264_quant_8x8_avx2, stop reason = EXC_BAD_ACCESS (code=EXC_I386_GPFLT)
    frame #0: 0x00000001011b6fa0 libx264.142.dylib`x264_quant_8x8_avx2
libx264.142.dylib`x264_quant_8x8_avx2:
->  0x1011b6fa0 <+0>:  vmovdqa (%rdi), %ymm1
    0x1011b6fa4 <+4>:  vmovdqa 0x20(%rdi), %ymm3
    0x1011b6fa9 <+9>:  vpabsw %ymm1, %ymm0
    0x1011b6fae <+14>: vpabsw %ymm3, %ymm2
(lldb) bt
* thread #2: tid = 0xc3f87, 0x00000001011b6fa0 libx264.142.dylib`x264_quant_8x8_avx2, stop reason = EXC_BAD_ACCESS (code=EXC_I386_GPFLT)
  * frame #0: 0x00000001011b6fa0 libx264.142.dylib`x264_quant_8x8_avx2
    frame #1: 0x00000001011779a3 libx264.142.dylib`x264_mb_encode_intra_block_mpeg2(h=0x0000000104ac7220, idx=0, i_qp=8) + 371 at macroblock.c:280
    frame #2: 0x0000000101172d30 libx264.142.dylib`x264_macroblock_encode + 2007 at macroblock.c:841
    frame #3: 0x0000000101172559 libx264.142.dylib`x264_macroblock_encode(h=0x0000000104ac7220) + 6521 at macroblock.c:1171
    frame #4: 0x0000000101133cc8 libx264.142.dylib`x264_rd_cost_mb(h=0x0000000104ac7220, i_lambda2=3686) + 136 at rdo.c:175
    frame #5: 0x000000010113c26e libx264.142.dylib`x264_intra_rd(h=0x0000000104ac7220, a=0x000000010557d380, i_satd_thresh=268435456) + 78 at analyse.c:1237
    frame #6: 0x00000001011397b1 libx264.142.dylib`x264_macroblock_analyse(h=0x0000000104ac7220) + 6001 at analyse.c:3429
    frame #7: 0x0000000101188a2d libx264.142.dylib`x264_slice_write(h=0x0000000104ac7220) + 2333 at encoder.c:2896
    frame #8: 0x00000001011860bb libx264.142.dylib`x264_slices_write(h=0x0000000104ac7220) + 395 at encoder.c:3286
    frame #9: 0x000000010118b353 libx264.142.dylib`x264_threadpool_thread(pool=0x00000001034032a0) + 163 at threadpool.c:69