The problem was that my_hash_sort didn't properly delete end-space characters properly, so strings that should compare
identically was seen as different strings.  (Space was handled correctly, but not NBSP)
This caused duplicate key errors when a heap table was converted to Aria as part of overflow in group by.

Fixed by removing all characters that compares as end space when creating a hash.

Other things:
- Fixed that --sorted_results also works for errors in mysqltest.
- Speed up hash by not comparing strings that has different hash.
- Speed up many my_hash_sort functions by using registers to calculate hash instead of pointers.
  This was previously done for some functions, but not for all.
- Made a macro of the hash function, to simplify code and to be able to experiment with new hash functions.







client/mysqltest.cc:
  Fixed that --sorted_results also works for error messages.
mysql-test/r/ctype_partitions.result:
  New test to ensure that partitions on hash works
mysql-test/suite/multi_source/gtid.result:
  Updated result
mysql-test/suite/multi_source/gtid.test:
  Test that --sorted_result works for error messages
mysql-test/suite/multi_source/gtid_ignore_duplicates.result:
  Updated result
mysql-test/suite/multi_source/gtid_ignore_duplicates.test:
  Updated result
mysql-test/suite/multi_source/load_data.result:
  Updated result
mysql-test/suite/multi_source/load_data.test:
  Updated result
mysql-test/t/ctype_partitions.test:
  New test to ensure that partitions on hash works
storage/heap/hp_write.c:
  Speed up hash by not comparing strings that has different hash.
storage/maria/ma_check.c:
  Extra debug
strings/ctype-bin.c:
  Use macro for hash function
strings/ctype-latin1.c:
  Use macro for hash function
  Use registers to calculate hash (speedup)
strings/ctype-mb.c:
  Use macro for hash function
  Use registers to calculate hash (speedup)
strings/ctype-simple.c:
  Use macro for hash function
  Use same variable names as in other my_hash_sort functions.
  Update my_hash_sort_simple() to properly remove end space (patch by Bar)
strings/ctype-uca.c:
  Ignore duplicated space inside strings and end space in my_hash_sort_uca(). This fixed MDEV-6255
  Use macro for hash function
  Use registers to calculate hash (speedup)
strings/ctype-ucs2.c:
  Use macro for hash function
  Use registers to calculate hash (speedup)
strings/ctype-utf8.c:
  Use macro for hash function
  Use registers to calculate hash (speedup)
strings/strings_def.h:
  Made a macro of the hash function, to simplify code and to be able to experiment with new hash functions.