cleanup: partition_info::check_constants

partition_info had a bunch of function pointers to avoid if()'s when invoking part_type specific functionality (like get_part_id, etc). But check_range_constants() and check_list_constants() were still invoked conditionally, with if()'s. Create partition_info::check_constants function pointer, get rid of if()'s Also remove alloc argument of check_range_constants(), added in 26a3ff0. Broken system versioning will be fixed in following commits.

Author: vuvova

sql/ha_partition.cc

@@ -8017,7 +8017,7 @@ int ha_partition::compare_number_of_records(ha_partition *me,
  ::info() is used to return information to the optimizer.
  Currently this table handler doesn't implement most of the fields
  really needed. SHOW also makes use of this data
- Another note, if your handler doesn't proved exact record count,
+ Another note, if your handler doesn't provide exact record count,
  you will probably want to have the following in your code:
  if (records < 2)
  records = 2;