Made mysql_make_view() to call destructor for st_lex_local objects before
throwing them away (this happens in case of error).


sql/sql_lex.h:
  Made LEX's destructor virtual to be able properly destroy objects
  of inherited classes (i.e. of st_lex_local).
sql/sql_view.cc:
  mysql_make_view():
    We should call destructor for st_lex_local object before throwing
    it away.