minor cleanups
XA tests


include/m_ctype.h:
  minor cleanup
sql/field.cc:
  minor cleanup
sql/handler.cc:
  XID SQL syntax
sql/handler.h:
  XID SQL syntax
sql/item_sum.h:
  minor cleanup
sql/lock.cc:
  comments
sql/sql_class.cc:
  minor cleanup
sql/sql_lex.h:
  XID SQL syntax
sql/sql_parse.cc:
  XID SQL syntax
sql/sql_yacc.yy:
  XID SQL syntax
  cleanups