Issue 11170

The implementation of 'osl_executeProcess()' internally uses a thread which in
turn starts (and wait()'s on) the requested process.

The thread start routine 'ChildStatusProc()' and 'osl_executeProcess()'
communicate via a shared data structure containing some file handles and a
condition variable that is signaled when the child process has been started.

The race condition occurs should execution of the child process fail. In this
case the shared data structure is accessed after the condition is signaled,
such that the parent thread may have destroyed that shared data, already, which
more often that not results in a SEGV.

In the case of child process execution success, the code has the correct order
of instructions and there's no race condition.