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.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@84903 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/System/Unix/Program.inc b/lib/System/Unix/Program.inc
index 56dea25..c52f3a88 100644
--- a/lib/System/Unix/Program.inc
+++ b/lib/System/Unix/Program.inc
@@ -244,7 +244,7 @@
   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);