fix less compare for address and bytes32

[kjx98]

"load64be(&a.bytes[8]) == load64be(&b.bytes[8])" requires "load64be(&a.bytes[0]) == load64be(&b.bytes[0]" as well, check if load64be(&a.bytes[0]) > load64be(&b.bytes[0] and "load64be(&a.bytes[8]) == load64be(&b.bytes[8])"

[codecov-io]

Codecov Report

Merging #498 into master will increase coverage by 0.03%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master     #498      +/-   ##
==========================================
+ Coverage   91.93%   91.97%   +0.03%     
==========================================
  Files          20       20              
  Lines        3076     3089      +13     
==========================================
+ Hits         2828     2841      +13     
  Misses        248      248

[chfast]

Do you have unit tests for these cases?

[kjx98]

add unit test to test/unittests/cpp_test.cpp
z_max stands 0x00000000 00000000 (64 bits) leading 0 for address/bytes32
max_z tailing with 64 bits 0

[chfast]

Thanks for the fix.