MYSQL_TYPE_NEWDECIMAL

Added support for the type MYSQL_TYPE_NEWDECIMAL. It now works like
MYSQL_TYPE_DECIMAL. Unfortunately there cannot be a test case until
we have a working information_schema plugin as part of the source
distribution.


sql/sql_show.cc:
  Bug#34367: The fix. Corrected wrong comments and a DBUG_ENTER with wrong 
  function name.
sql/table.h:
  Bug#34367: Added comments to st_field_info.