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/Plugins/Process/gdb-remote/ProcessGDBRemote.cpp b/source/Plugins/Process/gdb-remote/ProcessGDBRemote.cpp
index 8424d2a..53b7a24 100644
--- a/source/Plugins/Process/gdb-remote/ProcessGDBRemote.cpp
+++ b/source/Plugins/Process/gdb-remote/ProcessGDBRemote.cpp
@@ -1125,7 +1125,7 @@
             tid_t tid = thread_ids[i];
             ThreadSP thread_sp (old_thread_list.FindThreadByID (tid, false));
             if (!thread_sp)
-                thread_sp.reset (new ThreadGDBRemote (*this, tid));
+                thread_sp.reset (new ThreadGDBRemote (shared_from_this(), tid));
             new_thread_list.AddThread(thread_sp);
         }
     }
@@ -1201,7 +1201,7 @@
                     if (!thread_sp)
                     {
                         // Create the thread if we need to
-                        thread_sp.reset (new ThreadGDBRemote (*this, tid));
+                        thread_sp.reset (new ThreadGDBRemote (shared_from_this(), tid));
                         m_thread_list.AddThread(thread_sp);
                     }
                 }
@@ -1292,7 +1292,7 @@
                         else if (reason.compare("breakpoint") == 0)
                         {
                             addr_t pc = gdb_thread->GetRegisterContext()->GetPC();
-                            lldb::BreakpointSiteSP bp_site_sp = gdb_thread->GetProcess().GetBreakpointSiteList().FindByAddress(pc);
+                            lldb::BreakpointSiteSP bp_site_sp = gdb_thread->GetProcess()->GetBreakpointSiteList().FindByAddress(pc);
                             if (bp_site_sp)
                             {
                                 // If the breakpoint is for this thread, then we'll report the hit, but if it is for another thread,
@@ -1335,7 +1335,7 @@
                             // Currently we are going to assume SIGTRAP means we are either
                             // hitting a breakpoint or hardware single stepping. 
                             addr_t pc = gdb_thread->GetRegisterContext()->GetPC();
-                            lldb::BreakpointSiteSP bp_site_sp = gdb_thread->GetProcess().GetBreakpointSiteList().FindByAddress(pc);
+                            lldb::BreakpointSiteSP bp_site_sp = gdb_thread->GetProcess()->GetBreakpointSiteList().FindByAddress(pc);
                             if (bp_site_sp)
                             {
                                 // If the breakpoint is for this thread, then we'll report the hit, but if it is for another thread,