<rdar://problem/10103468>

I started work on being able to add symbol files after a debug session
had started with a new "target symfile add" command and quickly ran into
problems with stale Address objects in breakpoint locations that had 
lldb_private::Section pointers into modules that had been removed or 
replaced. This also let to grabbing stale modules from those sections. 
So I needed to thread harded the Address, Section and related objects.

To do this I modified the ModuleChild class to now require a ModuleSP
on initialization so that a weak reference can created. I also changed
all places that were handing out "Section *" to have them hand out SectionSP.
All ObjectFile, SymbolFile and SymbolVendors were inheriting from ModuleChild
so all of the find plug-in, static creation function and constructors now
require ModuleSP references instead of Module *. 

Address objects now have weak references to their sections which can
safely go stale when a module gets destructed. 

This checkin doesn't complete the "target symfile add" command, but it
does get us a lot clioser to being able to do such things without a high
risk of crashing or memory corruption.

llvm-svn: 151336
diff --git a/lldb/source/Symbol/Block.cpp b/lldb/source/Symbol/Block.cpp
index 886144d..627a5d4 100644
--- a/lldb/source/Symbol/Block.cpp
+++ b/lldb/source/Symbol/Block.cpp
@@ -158,12 +158,12 @@
     sc->block = this;
 }
 
-Module *
+lldb::ModuleSP
 Block::CalculateSymbolContextModule ()
 {
     if (m_parent_scope)
         return m_parent_scope->CalculateSymbolContextModule ();
-    return NULL;
+    return lldb::ModuleSP();
 }
 
 CompileUnit *
@@ -388,7 +388,7 @@
         LogSP log(lldb_private::GetLogIfAllCategoriesSet (LIBLLDB_LOG_SYMBOLS));
         if (log)
         {
-            Module *module = m_parent_scope->CalculateSymbolContextModule();
+            ModuleSP module_sp (m_parent_scope->CalculateSymbolContextModule());
             Function *function = m_parent_scope->CalculateSymbolContextFunction();
             const addr_t function_file_addr = function->GetAddressRange().GetBaseAddress().GetFileAddress();
             const addr_t block_start_addr = function_file_addr + range.GetRangeBase ();
@@ -408,8 +408,8 @@
                              block_end_addr,
                              parent_block->GetID(),
                              function->GetID(),
-                             module->GetFileSpec().GetDirectory().GetCString(),
-                             module->GetFileSpec().GetFilename().GetCString());
+                             module_sp->GetFileSpec().GetDirectory().GetCString(),
+                             module_sp->GetFileSpec().GetFilename().GetCString());
             }
             else
             {
@@ -420,8 +420,8 @@
                              block_end_addr,
                              parent_block->GetID(),
                              function->GetID(),
-                             module->GetFileSpec().GetDirectory().GetCString(),
-                             module->GetFileSpec().GetFilename().GetCString());
+                             module_sp->GetFileSpec().GetDirectory().GetCString(),
+                             module_sp->GetFileSpec().GetFilename().GetCString());
             }
         }
         parent_block->AddRange (range);