[PATCH] TLS for MinGW

[Yaron Keren]

  It looks like LLVM has TLS support, in lib\Target\X86\X86ISelLowering.cpp:8550

    if (Subtarget->isTargetKnownWindowsMSVC() ||
        Subtarget->isTargetWindowsGNU()) {
      // Just use the implicit TLS architecture

  and test\CodeGen\X86\tls* do test for triple==x86-pc-win32, x86_64-pc-win32

http://reviews.llvm.org/D3421