Patch from Matt Kopec:

This patch fixes an issue where if lldb fails to attach to a process (ie. invalid pid) on Linux, the process monitor thread gets stuck waiting for a signal from the attach thread, which never comes due to not being signaled. It also implements StopOpThread which is used for both attach/launch cases as I'm not aware of any special handling needed for the attach case. Also, propagate 'Error' from the Detach function instead of using a bool.

llvm-svn: 166055
diff --git a/lldb/source/Plugins/Process/Linux/ProcessMonitor.h b/lldb/source/Plugins/Process/Linux/ProcessMonitor.h
index 03e8c8c..4594ff4 100644
--- a/lldb/source/Plugins/Process/Linux/ProcessMonitor.h
+++ b/lldb/source/Plugins/Process/Linux/ProcessMonitor.h
@@ -158,7 +158,7 @@
     bool
     BringProcessIntoLimbo();
 
-    bool
+    lldb_private::Error
     Detach();
 
 
@@ -213,9 +213,6 @@
     void
     StartLaunchOpThread(LaunchArgs *args, lldb_private::Error &error);
 
-    void
-    StopLaunchOpThread();
-
     static void *
     LaunchOpThread(void *arg);
 
@@ -238,9 +235,6 @@
     void
     StartAttachOpThread(AttachArgs *args, lldb_private::Error &error);
 
-    void
-    StopAttachOpThread();
-
     static void *
     AttachOpThread(void *args);
 
@@ -287,6 +281,10 @@
     void 
     StopMonitor();
 
+    /// Stops the operation thread used to attach/launch a process.
+    void
+    StopOpThread();
+
     void
     CloseFD(int &fd);
 };