Cross Reference: /external/libcxx/test/std/thread/thread.mutex/thread.once/thread.once.onceflag

`Name`	`Date`	`Size`
Up to higher level directory
`assign.fail.cpp`	21-Aug-2018	`534`
`copy.fail.cpp`	21-Aug-2018	`514`
`default.pass.cpp`	21-Aug-2018	`619`