Counterpart to Once.initEnter. Expects a location of a static
0-initialized initialization variable, and an initialization value
other than 0. Sets the variable to the initialization value, and
releases concurrent threads blocking in Once.initEnter on this
initialization variable.
Counterpart to Once.initEnter. Expects a location of a static 0-initialized initialization variable, and an initialization value other than 0. Sets the variable to the initialization value, and releases concurrent threads blocking in Once.initEnter on this initialization variable.