Primitive attach support for linux

This patch is a starting point for the attach functionality.

Signed-off-by: Johnny Chen <johnny.chen@apple.com>

git-svn-id: https://llvm.org/svn/llvm-project/llvdb/trunk@133006 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/source/Plugins/Process/Linux/ProcessLinux.cpp b/source/Plugins/Process/Linux/ProcessLinux.cpp
index c4ce8ee..e6940fe 100644
--- a/source/Plugins/Process/Linux/ProcessLinux.cpp
+++ b/source/Plugins/Process/Linux/ProcessLinux.cpp
@@ -105,7 +105,16 @@
 Error
 ProcessLinux::DoAttachToProcessWithID(lldb::pid_t pid)
 {
-    return Error(1, eErrorTypeGeneric);
+    Error error;
+    assert(m_monitor == NULL);
+
+    m_monitor = new ProcessMonitor(this, pid, error);
+
+    if (!error.Success())
+        return error;
+
+    SetID(pid);
+    return error;
 }
 
 Error