Use predicated ConditionVariable::wait in Awaiter
Use predicated ConditionVariable::wait in Awaiter

This reduces the amount of code involved in waiting for the condition
variable. As a side effect, it takes the protect call out of the loop,
which should cause less locking operations.

MasterDuke17/rakudo,MasterDuke17/rakudo,MasterDuke17/rakudo,tbrowder/rakudo,MasterDuke17/rakudo,tbrowder/rakudo,tbrowder/rakudo,tony-o/rakudo,labster/rakudo,salortiz/rakudo,salortiz/rakudo,labster/rakudo,rakudo/rakudo,MasterDuke17/rakudo,MasterDuke17/rakudo,labster/rakudo,rakudo/rakudo,tony-o/rakudo,labster/rakudo,salortiz/rakudo,tony-o/rakudo,tony-o/rakudo,rakudo/rakudo,salortiz/rakudo,salortiz/rakudo,rakudo/rakudo,tbrowder/rakudo,labster/rakudo,tbrowder/rakudo,labster/rakudo,rakudo/rakudo,rakudo/rakudo,tony-o/rakudo,salortiz/rakudo,tbrowder/rakudo,tony-o/rakudo