Thread hardening part 3. Now lldb_private::Thread objects have std::weak_ptr
objects for the backlink to the lldb_private::Process. The issues we were
running into before was someone was holding onto a shared pointer to a 
lldb_private::Thread for too long, and the lldb_private::Process parent object
would get destroyed and the lldb_private::Thread had a "Process &m_process"
member which would just treat whatever memory that used to be a Process as a
valid Process. This was mostly happening for lldb_private::StackFrame objects
that had a member like "Thread &m_thread". So this completes the internal
strong/weak changes.

Documented the ExecutionContext and ExecutionContextRef classes so that our
LLDB developers can understand when and where to use ExecutionContext and 
ExecutionContextRef objects.



git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@151009 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/source/Target/ThreadPlanCallUserExpression.cpp b/source/Target/ThreadPlanCallUserExpression.cpp
index 6352edb..b46d6b4 100644
--- a/source/Target/ThreadPlanCallUserExpression.cpp
+++ b/source/Target/ThreadPlanCallUserExpression.cpp
@@ -64,7 +64,7 @@
 {
     StopInfoSP stop_info_sp = ThreadPlanCallFunction::GetRealStopInfo();
     lldb::addr_t addr = GetStopAddress();
-    DynamicCheckerFunctions *checkers = m_thread.GetProcess().GetDynamicCheckers();
+    DynamicCheckerFunctions *checkers = m_thread.GetProcess()->GetDynamicCheckers();
     StreamString s;
     
     if (checkers && checkers->DoCheckersExplainStop(addr, s))