Revision of Brian's threading support library to be a bit more generic and

platform independent.  This code is completely untested (but never used),
and needs autoconf support for detecting pthreads, but it's a start, and
deletes two emails from my inbox.  :)


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@10906 91177308-0d34-0410-b5e6-96231b3b80d8

include/Support/ThreadSupport-NoSupport.h

@@ -0,0 +1,34 @@
+//===-- Support/ThreadSupport-NoSupport.h - Generic impl --------*- C++ -*-===//
+// 
+//                     The LLVM Compiler Infrastructure
+//
+// This file was developed by the LLVM research group and is distributed under
+// the University of Illinois Open Source License. See LICENSE.TXT for details.
+// 
+//===----------------------------------------------------------------------===//
+//
+// This file defines a generic ThreadSupport implementation used when there is
+// no supported threading mechanism on the current system.  Users should never
+// #include this file directly!
+//
+//===----------------------------------------------------------------------===//
+
+// Users should never #include this file directly!  As such, no include guards
+// are needed.
+
+#ifndef SUPPORT_THREADSUPPORT_H
+#error "Code should not #include Support/ThreadSupport-NoSupport.h directly!"
+#endif
+
+namespace llvm {
+  /// Mutex - This class allows user code to protect variables shared between
+  /// threads.  It implements a "recursive" mutex, to simplify user code.
+  ///
+  /// Since there is no platform support for _creating threads_, the non-thread
+  /// implementation of this class is a noop.
+  ///
+  struct Mutex {
+    void acquire () {}
+    void release () {}
+  };
+}