lowlevel-blt-bench: Add over_8888_8_0565 test
armv6: Add over_8888_8_0565 fast path

lowlevel-blt-bench results:

    Before          After
    Mean   StdDev   Mean   StdDev  Confidence  Change
L1  5.2    0.0      20.0   0.2     100.0%      +281.7%
L2  4.5    0.0      16.2   0.2     100.0%      +256.9%
M   4.5    0.0      18.8   0.0     100.0%      +321.1%
HT  3.9    0.0      10.9   0.0     100.0%      +177.6%
VT  3.9    0.0      10.6   0.0     100.0%      +171.5%
R   3.8    0.0      10.0   0.0     100.0%      +165.1%
RT  2.3    0.0      4.9    0.1     100.0%      +107.7%
armv6: Add over_8888_n_0565 fast path

lowlevel-blt-bench results:

    Before          After
    Mean   StdDev   Mean   StdDev  Confidence  Change
L1  5.7    0.0      20.6   0.1     100.0%      +263.8%
L2  4.9    0.0      17.4   0.3     100.0%      +254.0%
M   4.8    0.0      19.9   0.0     100.0%      +312.9%
HT  4.5    0.0      12.4   0.1     100.0%      +175.4%
VT  4.5    0.0      12.0   0.0     100.0%      +168.9%
R   4.3    0.0      11.4   0.1     100.0%      +163.3%
RT  2.9    0.0      6.0    0.1     100.0%      +106.9%