don't define UNIV_DEBUG in CFLAGS/CXXFLAGS anymore
sql/mysqld.cc
    hide from the user options that do nothing
sql/sql_update.cc
    better fix for uninitialized used_index


configure.in:
  don't define UNIV_DEBUG in CFLAGS/CXXFLAGS anymore
sql/mysqld.cc:
  hide from the user options that do nothing
sql/sql_update.cc:
  better fix for uninitialized used_index