[Heimdal-source-changes] [heimdal/heimdal] cc0e92: base: correct Windows heim_base_once_f semantics

[GitHub]

  Branch: refs/heads/master
  Home:   https://github.com/heimdal/heimdal
  Commit: cc0e92a3c359cb34079b8e5b258ceef813ea684a
      https://github.com/heimdal/heimdal/commit/cc0e92a3c359cb34079b8e5b258ceef813ea684a
  Author: Nicolas Williams <nico at cryptonector.com>
  Date:   2015-11-30 (Mon, 30 Nov 2015)

  Changed paths:
    M lib/base/heimbase.c
    M lib/base/heimbase.h

  Log Message:
  -----------
  base: correct Windows heim_base_once_f semantics

As implemented by Jeffrey Altman heim_base_once_f() is a variant of the
"double-checked gate lock pattern".   Full memory barriers must be used
when determining whether or not to call SwitchToThread().

Change-Id: I2f8446a56c50a37c921d6e993433c9a3f7488f50