BUG#16002: Make partition functions that are unsigned work properly

mysql-test/r/partition.result:
  A number of new test cases for unsigned partition functions
mysql-test/r/partition_error.result:
  A number of new test cases for unsigned partition functions
mysql-test/r/partition_range.result:
  A number of new test cases for unsigned partition functions
mysql-test/t/partition.test:
  A number of new test cases for unsigned partition functions
mysql-test/t/partition_error.test:
  A number of new test cases for unsigned partition functions
mysql-test/t/partition_range.test:
  A number of new test cases for unsigned partition functions
sql/ha_partition.cc:
  Error message for no partition found needs to take signed/unsigned into account when printing erroneus value
sql/partition_element.h:
  Introduced signed_flag and max_value flag on partition elements
  Also list is now a list of a struct rather than simply longlong values
  Small rearranges of order
sql/partition_info.cc:
  Introduced signed_flag and max_value flag on partition elements
  Also list is now a list of a struct rather than simply longlong values
  Small rearranges of order
  Lots of new code to handle checks of proper definition of table when
  partition function is unsigned
sql/partition_info.h:
  Mostly rearrangement of code and some addition of a THD object in check_partition_info call
  plus a new method for comparing unsigned values
sql/share/errmsg.txt:
  Negative values not ok for unsigned partition functions
sql/sql_partition.cc:
  Fixed a multi-thread bug (when defining several partitioned tables in parallel)
  New code to generate partition syntax that takes into account sign of constants.
  Made function fix_fields_part_func more reusable.
  Fixed a number of get_partition_id functions for range and list and similar functions
  for partition pruning code.
  Unfortunately fairly much duplication of code with just small changes.
sql/sql_partition.h:
  New function headers
sql/sql_show.cc:
  Changed list of values for LIST partitioned tables
  Also fixed printing of unsigned values in INFORMATION SCHEMA for partitioned table
sql/sql_table.cc:
  Fixed for new interface
sql/sql_yacc.yy:
  Moved definition of struct to partition_element.h
  Added code to keep track of sign of constants in
  RANGE and LIST partitions
sql/table.cc:
  Fixed for new interface

mysql-test/r/partition_error.result

@@ -554,3 +554,7 @@ PARTITION BY RANGE (a) (PARTITION p1 VALUES LESS THAN(5));
 insert into t1 values (10);
 ERROR HY000: Table has no partition for value 10
 drop table t1;
+create table t1 (a bigint unsigned)
+partition by range (a)
+(partition p0 values less than (-1));
+ERROR HY000: Partition function is unsigned, cannot have negative constants