Use 'waitpid' instead of 'wait'. Basing Program::Wait() on 'wait()' prevents it being correct within a multithreaded context.

This address: PR 5277 (Program::Wait is unsafe to call from multiple threads).

Note: If waitpid() turns out to be non-portable, we can add more autoconf magic, or look into
another solution.

llvm-svn: 84903

lib/System/Unix/Program.inc

@@ -244,7 +244,7 @@ Program::Wait(unsigned secondsToWait,
   int status;
   uint64_t pid = reinterpret_cast<uint64_t>(Data_);
   pid_t child = static_cast<pid_t>(pid);
-  while (wait(&status) != child)
+  while (waitpid(pid, &status, 0) != child)
     if (secondsToWait && errno == EINTR) {
       // Kill the child.
       kill(child, SIGKILL);