<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

lldb/source/API/SBThread.cpp

@@ -635,7 +635,7 @@ SBThread::RunToAddress (lldb::addr_t addr)
         bool abort_other_plans = true;
         bool stop_other_threads = true;
 
-        Address target_addr (NULL, addr);
+        Address target_addr (addr);
 
         Thread *thread = exe_ctx.GetThreadPtr();
         Process *process = exe_ctx.GetProcessPtr();