mysql-test/r/mdl_sync.result:
  Full merge with 5.6
mysql-test/t/mdl_sync.test:
  Full merge with 5.6
sql/debug_sync.cc:
  Full merge with 5.6
sql/debug_sync.h:
  Full merge with 5.6
sql/mdl.cc:
  Full merge with 5.6
sql/sql_base.cc:
  Removed code not in 5.6 anymore