ProjectNodes: Fix line() method

Actually return the value of the m_line member varibale instead of -1.

Change-Id: I23ee47638e9b35cafcedca827790b4c2e0a02462
Reviewed-by: Daniel Teske <daniel.teske@digia.com>

src/plugins/projectexplorer/projectnodes.cpp

@@ -161,7 +161,7 @@ QString Node::path() const
 
 int Node::line() const
 {
-    return -1;
+    return m_line;
 }
 
 QString Node::displayName() const