Add "vAttachOrWait" to debugserver, so you can implement "attach to the process if it exists OR wait for it" without race conditions.  Use that in lldb.

llvm-svn: 160578
diff --git a/lldb/source/API/SBTarget.cpp b/lldb/source/API/SBTarget.cpp
index 1dc30d1..7635a36 100644
--- a/lldb/source/API/SBTarget.cpp
+++ b/lldb/source/API/SBTarget.cpp
@@ -369,6 +369,18 @@
     m_opaque_sp->SetWaitForLaunch (b);
 }
 
+bool
+SBAttachInfo::GetIgnoreExisting ()
+{
+    return m_opaque_sp->GetIgnoreExisting();
+}
+
+void
+SBAttachInfo::SetIgnoreExisting (bool b)
+{
+    m_opaque_sp->SetIgnoreExisting (b);
+}
+
 uint32_t
 SBAttachInfo::GetUserID()
 {