<rdar://problem/13265297> 

StackFrame assumes m_sc is additive, but m_sc can lose its target. So now the SymbolContext::Clear() method takes a bool that indicates if the target should be cleared. Modified all existing code to properly set the bool argument.

llvm-svn: 175953
diff --git a/lldb/source/Symbol/Variable.cpp b/lldb/source/Symbol/Variable.cpp
index 8172875..309e392 100644
--- a/lldb/source/Symbol/Variable.cpp
+++ b/lldb/source/Symbol/Variable.cpp
@@ -203,7 +203,7 @@
     if (m_owner_scope)
         m_owner_scope->CalculateSymbolContext(sc);
     else
-        sc->Clear();
+        sc->Clear(false);
 }
 
 bool